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M Salmona

Publications and source records attributed to M Salmona.

At least 73 records · Page 4Linked to original sources
PubMed1995

Purification, cDNA cloning, and tissue distribution of bovine liver aldehyde oxidase.

Aldehyde oxidase was purified to homogeneity from bovine liver and primary structural information obtained by sequencing a series of cleavage peptides permitted the cloning of the corresponding cDNA. The cDNA is 4,630 base pairs long, and it consists of a 102-base pair 5'-untranslated region followed by a 4017-base pair coding region and a 511-base pair 3'-untranslated region. The open reading frame predicts a 1339-amino acid polypeptide with a calculated molecular weight of 147,441, which is consistent with the size of the aldehyde oxidase monomeric subunit. The aldehyde oxidase polypeptide contains consensus sequences for iron-sulfur centers and a molybdopterin binding site. The amino acid sequence deduced from the cDNA shows significant similarity with that of xanthine dehydrogenases from various sources. The primary structure of bovine aldehyde oxidase is remarkably similar (approximately 86%) to that of the translation product of a cDNA recently isolated by Wright et al. (Wright, R. M., Vaitaitis, G. M., Wilson, C. M., Repine, T. B., Terada, L. S., and Repine, J. E. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 10690-10694) and reported to represent human xanthine dehydrogenase. With the help of a monospecific antibody raised against the purified protein and the isolated cDNA, the tissue distribution of the bovine aldehyde oxidase protein and corresponding mRNA was determined. Aldehyde oxidase is expressed at high levels in liver, lung, and spleen, and, at a much lower level, in many other organs.

Aldehyde Oxidase↗
PubMed1995

Phosphatidic acid and lysophosphatidic acid induce haptotactic migration of human monocytes.

The present study was aimed at defining the chemotactic activity of phosphatidic acid, which is rapidly produced by phagocytes in response to chemotactic agonists. Exogenously added phosphatidic acid induced human monocyte directional migration across polycarbonate filters with an efficacy (number of cell migrated) comparable to that of "classical" chemotactic factors. In lipid specificity studies, activity of phosphatidic acid decreased with increasing acyl chain length but was restored by introducing unsaturation in the acyl chain with the most active form being the natural occurring 18:0,20:4-phosphatidic acid. Lysophosphatidic acid was also active in inducing monocyte migration. No other phospholipid and lysophospholipid tested was effective in this response. Monocyte migration was regulated by a gradient of phosphatidic acid and lysophosphatidic acid bound to the polycarbonate filter, in the absence of detectable soluble chemoattractant. Migration was also observed if phospholipids were bound to fibronectin-coated polycarbonate filters. Thus, phosphatidic acid and lysophosphatidic acid, similarly to other physiological chemoattractants (e.g. C5a and interleukin-8), induce cell migration by an haptotactic mechanism. Phosphatidic acid caused a rapid increase of filamentous actin and, at higher concentrations, induced a rise of intracellular calcium concentration. Monocyte migration to phosphatidic acid and lysophosphatidic acid, but not to diacylglycerol, was inhibited in a concentration-dependent manner by Bordetella pertussis toxin, while cholera toxin was ineffective. In the chemotactic assay, phosphatidic acid and lysophosphatidic acid induced a complete homologous desensitization and only partially cross-desensitized one with each other, or with diacyl-glycerol and monocyte chemotactic protein-1. Suramine inhibited monocyte chemotaxis with a different efficiency phosphatidic acid > lysophosphatidic acid" diacyl-glycerol On the contrary, monocyte chemotactic protein-1-induced chemotaxis was not affected by the drug. Collectively, these data show that phosphatidic acid induces haptotactic migration of monocytes that is at least in part receptor-mediated. These results support a role for phosphatidic acid and lysophosphatidic acid in the regulation of leukocyte accumulation into tissues.

Actins↗
PubMed1995

Extracellular glutamate levels in the hypothalamus and hippocampus of rats after acute or chronic oral intake of monosodium glutamate.

Using brain microdialysis we studied the effect of high doses of monosodium glutamate (MSG) on the extracellular concentration of glutamate in the hypothalamus and in the hippocampus of freely moving rats. MSG at 4 g/kg (40% solution) given by gavage caused a significant increase in plasma (5.3 +/- 0.4-fold, P < 0.01) and extracellular glutamate in the hippocampus (4.2 +/- 0.6-fold, P < 0.01) and in the hypothalamus (8.9 +/- 1.7-fold, P < 0.01) compared to control rats receiving a 40% sucrose solution (10 ml/kg). The peak increase was found within 40 min after MSG administration then declining to baseline in the next 80 min. No changes were found in glutamate tissue concentrations. Twenty-one days after ad libitum MSG intake with the diet (approximately 4 g/kg) no changes were found, in plasma, in extracellular and tissue concentration of glutamate in the hypothalamus compared to rats fed with a normal diet. Glutamate release induced by 200 mM KCl was not modified as well. Histological analysis of Nissl-stained brain tissue slices did not reveal any obvious cell loss in the hippocampus after acute or chronic MSG administration.

Administration, Oral↗
PubMed1995

Manganese peroxidase from Phanerochaete chrysosporium. A homology-based molecular model.

A detailed three-dimensional model of manganese peroxidase was constructed using lignine peroxidase as the structural scaffold. This is the only protein in the peroxidase family except for cytochrome c peroxidase for which a resolved crystal structure is available. The model was built using the following procedure: (a) structurally preserved regions were derived from similar regions in the sequence alignment of the two proteins; (b) non-similar regions were modelled by searching a set of resolved protein structures for fragments which fitted in geometrically and choosing the best fitting fragment. Side chains were constructed by calculating rotamer-rotamer interaction energies and minimizing intramolecular energy. Model refinement was performed by molecular mechanics calculation. The quality of the model was assessed on the basis of the propensity of the amino acids to be inserted into regular secondary-structure elements and to be exposed to solvent. All the lignine peroxidase regions not used for model construction because of the lack of similarity, except the helix fragment Leu261-Phe269, correspond to external loops, suggesting reliable modelling. The manganese peroxidase model structure was analyzed in detail and several functionally relevant structural features were predicted, the most important being: (a) the very close structural similarity between lignine and manganese peroxidase active sites, suggesting a similar mode of hydrogen peroxide activation; (b) the substitution of polar residues for the hydrophobic amino acids exposed at the edge of the channel involved in substrate recognition in lignine peroxidase, suggesting that manganese peroxidase does not directly bind aromatic substrates; (c) the location of residues potentially able to bind Mn2+, spatially positioned on the side of the 3-CH3 heme edge.

Amino Acid Sequence↗
PubMed1995

The imbalance of brain large-chain aminoacid availability in amyotrophic lateral sclerosis patients treated with high doses of branched-chain aminoacids.

Following the report of an increased mortality among patients with amyotrophic lateral sclerosis given high daily doses of branched-chain aminoacids, we assessed the plasma concentrations of large neutral aminoacids and glutamic acid and the large neutral aminoacid brain influx in 24 amyotrophic lateral sclerosis patients receiving placebo or branched-chain aminoacids (L-leucine 12 g, L-isoleucine 6 g, L-valine 6 g daily), in 15 untreated amyotrophic lateral sclerosis patients and in 15 healthy volunteers. The branched-chain aminoacid plasma concentrations increased three- to six-fold in the treated group compared to the patients receiving placebo or no treatment and to the healthy controls. Plasma glutamic acid concentrations in healthy volunteers were 51.59 +/- 7.53 nmol/ml while in the amyotrophic lateral sclerosis patients receiving no treatment, placebo or branched-chain aminoacids were 92.33 +/- 12.15 nmol/ml, 91.21 +/- 15.86 nmol/ml and 95.08 +/- 17.96 nmol/ml respectively. The glutamic acid concentration was significantly higher (P < 0.01) in amyotrophic lateral sclerosis patients than in healthy individuals. Plasma phenylalanine and tyrosine were lower in the amyotrophic lateral sclerosis patients than in healthy controls, regardless of treatment, whereas tryptophan levels were not significantly different. The branched-chain aminoacid brain influx of the treated group was 110-140% of that measured in the patients receiving placebo and in the healthy controls. The aromatic aminoacid brain influx was lower in the treated group than in the placebo group or healthy controls. An impairment of brain large neutral aminoacid availability might possible contribute to enhancing the progression of symptoms in patients with amyotrophic lateral sclerosis.

Adult↗
PubMed1995

Reye's and Reye-like syndromes, drug-related diseases? (causative agents, etiology, pathogenesis, and therapeutic approaches).

In the literature the separation between RS and RLS is confusing and makes it difficult to plan an appropriate preventive action or to develop new therapeutic approaches. We suggest that the generalized damage and encephalopathy seen in both RS and RLS may be due to a wide variety of causative agents that contribute to a common derangement, principally involving mitochondrial oxidative pathway. Fasting status and infections increase the catabolism and the subsequent flux of metabolites from peripheral tissues to the liver (FA and amino acids); cytokines (TNF, IL-1, and IL-6), in particular, mediate this effect during infection and experimental endotoxemia. Some drugs and other toxic compounds induce functional and morphological liver mitochondrial derangement. Oxidative metabolism is impaired, with subsequent stimulation of alternative pathways of oxidation, following production of unusual toxic acyl CoAs and dicarboxylic acids. Toxic compounds accumulate in the liver, deranging its functions and causing energy depletion, and are also released in the circulation from which they reach other tissues, including the brain. Neurons and astrocytes in the brain may be affected differently: Neurons suffer from the lack of energy and the effect of toxic compounds arriving from the bloodstream, and astrocytes may be directly affected by the beta-oxidation derangement. Very important may be genetic predisposition, which, by making the patient more sensitive to a particular causative agent, may facilitate the onset of RS and RLS. The therapeutic approach is, presently, mainly symptomatic, directed as it is to counteracting each alteration shown, depending by the clinical gravity. Other pharmacological approaches are only studied experimentally, like carnitine supplementation and PGE2 administration, or theoretically envisaged, like monoclonal antibody therapy directed at LPS or at pro-inflammatory cytokines or treatment with interferon-alpha.

Child↗
PubMed1995

Fate of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET18-OME) in malignant cells, normal cells, and isolated and perfused rat liver.

Ether lipids show high specific cytotoxicity in vitro on a wide variety of experimental tumors, but only moderate activity in vivo. One reason for this lack of activity in the whole animal might be a high degree of metabolic degradation. We therefore studied the biotransformation of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine ([3H]ET18-OMe) labeled in position 9-10 of the 1-alkyl chain, in rat plasma and erythrocytes, HL60 and K562 leukemic cells, HT29 adenocarcinoma cells, and cultured hepatocytes at 37 degrees C, and in a system of isolated and perfused rat liver. ET18-OMe and its metabolites were identified and quantified after lipid extraction and TLC separation. In tumor cells, 98% of ET18-OMe remained almost unmodified in vitro after 24-hr incubation. Plasma and erythrocytes from rats metabolized only 4-5% of the original compound in 3 hr. In cultured hepatocytes, 35% and 58.3%, respectively, of ET18-OMe was present after 6 and 24 hr as the metabolites 1-O-alkyl-2-O-methylglycerol (AMG), 1-O-alkyl-2-O-methylphosphatidic acid (AMPA), and stearyl alcohol (SA) (products of direct hydrolysis by phospholipases C and D and alkylhydrolase); phospholipids (phosphatidylcholine and phosphatidylethanolamine); and neutral lipids (products of secondary metabolism). In perfused rat liver, approximately 15% of the total radioactivity incorporated after 3 hr was distributed in metabolites as follows: 5.9% of AMPA, 5.0% of AMG, and 3.1% of SA. We conclude that the metabolism of ET18-OMe in normal tissues occurring through the same enzymes that metabolize natural lipids may partly explain the lack of effect in vivo.

Animals↗
PubMed1995

Intraluminal inflammation in the airways of patients with chronic bronchitis after treatment with Ambroxol.

Ambroxol is a mucus-modifying drug with a known ability to stimulate surfactant secretion and inhibit, in vitro, the production of proinflammatory cytokines, neutrophil chemotaxis, and Na+ absorption by the airway epithelium. In dogs inhaling ozone, bronchial hyperreactivity can be inhibited by aerosolized Ambroxol. To verify the possibility of producing anti-inflammatory effects in a clinically relevant condition, 20 patients with chronic bronchitis, randomly divided into two balanced matched groups, were submitted to a 14 day trial with Ambroxol, 150 mg.day-1, or placebo, according to a double-blind design. A bronchoalveolar lavage (BAL) was performed the day before starting treatment (T0) and at the 14th day (T14). The analysis of the cellular and soluble (total proteins, albumin, immunoglobulin G and A (IgG and IgA)) BAL components demonstrated no clear modifications. In particular, neutrophil values from the bronchial aliquot showed a large dispersion, with no significant differences (Ambroxol: T0 = 13.7 +/- 5.2%, T14 = 14.0 +/- 6.8%; placebo: T0 = 3.6 +/- 1.1%, T14 = 5.5 +/- 2.2%). We found a nonsignificant increase of phospholipids in BAL supernatants from Ambroxol-treated patients (2.5 +/- 1.9 vs 3.0 +/- 1.9 micrograms.mg-1 of protein); whilst in the placebo group data before and after treatment were superimposable (2.2 +/- 1.5 vs 2.3 +/- 1.9 micrograms.mg-1 of protein). In conclusion, we have failed to demonstrate that conventional treatment with oral Ambroxol can modify surfactant and BAL cell populations in the airways of patients with chronic bronchitis.

Ambroxol↗
PubMed1994

A neurotoxic prion protein fragment induces rat astroglial proliferation and hypertrophy.

Prion-related encephalopathies are characterized by the accumulation of an abnormal prion protein isoform (PrPSc) and the deposition of PrP amyloid in the brain. This process is accompanied by neuronal loss and astrogliosis. We recently showed that a synthetic peptide corresponding to residues 106-126 of human PrP is amyloidogenic and causes neuronal death by apoptosis in vitro. In the present study we investigated the effects of 1- and 14-day exposures of rat astroglial cultures to micromolar concentrations of this peptide as well as peptides homologous to other portions of PrP, a peptide corresponding to residues 25-35 of amyloid-beta protein, and a scrambled sequence of PrP 106-126. No significant changes were observed after 1-day exposure of cultures to any peptide. Conversely, 14-day treatment with PrP 106-126 (50 microM) resulted in a 5-fold increase in glial fibrillary acidic protein (GFAP) expression, as evaluated by Northern and Western blot analyses, and a 1.5-fold increment in cell number. Light and electron microscopy immunohistochemistry showed an enlargement in size and density of astroglial processes, and an increase in GFAP-immunoreactive intermediate filaments. These changes were not observed after 14-day treatment of cultures with the other peptides, including PrP 106-126 scrambled. The increase in GFAP expression of astroglial cultures exposed to PrP 106-126 was quantitatively similar to that found in scrapie-infected hamster brains.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

The induction of apoptosis is a common feature of the cytotoxic action of ether-linked glycerophospholipids in human leukemic cells.

The ability of 2 recent ether-lipid derivatives, aza-phospholipids BN52205 and BN52211, to induce apoptosis in different leukemia cell lines was investigated using I-octadecyl-2-methyl-rac-glycero-3- phosphocholine (ET-18-OCH3) as a positive control. HL60, K562, Molt-4 and U937 cells were exposed for 24 hr to 20 microM of drug. The 2 aza-derivatives were as cytotoxic as ET-18-OCH3: BN52205 and BN52211 selectively induced apoptotic death in HL60, Molt-4 and U937 cells, but not in the K562-resistant cell line. Around 50% of DNA was fragmented in HL60 cells after exposure to the aza-derivatives, and 34% and 20% of DNA was fragmented in Molt-4 and U937 cells respectively. Similar results were obtained when cells were exposed to ET-18-OCH3. Our data confirm that ether lipids induce apoptosis in a variety of human leukemic cells, providing a possible explanation for their selectivity and mechanism of action.

Antineoplastic Agents↗
PubMed1994

Conformational polymorphism of the amyloidogenic and neurotoxic peptide homologous to residues 106-126 of the prion protein.

Prion-related encephalopathies are characterized by cerebral accumulation of a post-translationally modified form of the cellular prion protein (PrPC), designated PrPSc. Evidence suggests that the conversion from PrPC to PrPSc involves changes in the secondary structure leading to an increase in beta-sheet content. We have previously shown that a synthetic peptide homologous to residues 106-126 of human PrP, belonging to a predicted alpha-helical domain, exhibits a beta-sheet conformation, forms amyloid-like fibrils, and is neurotoxic in vitro. The present study investigated how different chemicophysical conditions such as pH and ionic strength or a membrane-like environment influenced the secondary structure of this peptide. PrP 106-126 exhibited a predominantly beta-sheet structure in 200 mM phosphate buffer, pH 5.0, but a combination of beta-sheet and random coil structure in 200 mM phosphate buffer, pH 7.0, or in deionized water. The addition of trifluoroethanol (50% final concentration) to solutions of peptide in deionized water induced the appearance of an alpha-helical secondary structure, but did not modify the beta-sheet conformation of the peptide dissolved in 200 mM phosphate buffer, pH 5.0. In the presence of micelles formed by a 5% solution of sodium dodecyl sulfate, PrP 106-126 showed a high content of alpha-helix. When the peptide was dissolved in 5 mM phosphate buffer, pH 7.4, and incubated with liposomes, it changed from a prevalently random coil structure to a beta-sheet conformation. The environment-dependent conformational polymorphism of PrP 106-126 and its marked tendency to form stable beta-sheet structures at acidic pH could account for the shift from alpha-helix to beta-sheet associated with the conversion of PrPC to PrPSc, which occurs most likely in the endosomal-lysosomal compartment.

Amino Acid Sequence↗
PubMed1994

Molybdenum(VI) salts convert the xanthine oxidoreductase apoprotein into the active enzyme in mouse L929 fibroblastic cells.

The mouse L929 fibroblastic cell line presents low, but detectable, levels of the mRNA encoding xanthine oxidoreductase under basal conditions, and it responds to type I and type II interferons by inducing the expression of the transcript [Falciani, Ghezzi, Terao, Cazzaniga, and Garattini (1992) Biochem. J. 285, 1001-1008]. This cell line, however, does not show any detectable amount of xanthine oxidoreductase enzymic activity, either before or after treatment with the cytokines. Molybdenum(VI) salts, in the millimolar range, are capable of activating xanthine oxidoreductase in L929 cells both under basal conditions and after treatment with interferon-alpha. The increase is observed in mouse L929 as well as in clones derived from it, but not in many other human and mouse cell lines. The induction observed in L929 cells is post-translational in nature and it is insensitive to cycloheximide, indicating that the molybdenum ion converts a pool of inactive xanthine oxidoreductase apoenzyme into its holoenzymic form. When grown in the absence of sodium molybdate, the L929 cell line has undetectable intracellular levels of the molybdenum cofactor, since the cell extracts are unable to complement the nitrate reductase defect of the nit-1 mutant of Neurospora crassa. L929 cells grown in the presence of millimolar concentrations of sodium molybdate, however, become competent to complement the nit-1 defect. L929 cells accumulate molybdenum ion inside the intracellular compartment as efficiently as TEnd cells, a mouse endothelial cell line that expresses xanthine oxidoreductase activity both under basal conditions and after treatment with interferon-gamma, suggesting that L929 cells have a defect in one or more of the metabolic steps leading to the synthesis of the molybdenum cofactor.

3T3 Cells↗
PubMed1994

Biochemical effects of acute and subacute nitrogen dioxide exposure in rat lung and bronchoalveolar lavage fluid.

The pulmonary inflammatory response to NO2 exposure was measured by evaluating a series of biochemical and cellular parameters in rat bronchoalveolar lavage fluid. Animals were exposed to 9 mg/m3 (5 ppm) or 18 mg/m3 (10 ppm) of the gas for 24 h or 7 days. After bronchoalveolar lavage collection, a differential count of polymorphonuclear leukocytes, macrophages, and lymphocytes was done. A significant increase in polymorphonuclear leukocytes was found after 24 h of exposure, and after 7 days the number of macrophages increased significantly. After 7 days of exposure to 9 mg/m3 of NO2 (a dose that under our conditions did not induce migration of cells in the bronchoalveolar spaces) the ex vivo phorbol myristate acetate-induced superoxide anion production by resident cells was inhibited. After 24 h and 7 days of exposure to 18 mg/m3 of NO2, phorbol myristate acetate-induced superoxide anion production was lower than in the control group. The migration of polymorphonuclear leukocytes in the bronchoalveolar lavage fluid was not associated with any real increase in elastase. However, there was a dose- and time-dependent increase in alpha 1-proteinase inhibitor in response to both 9 and 18 mg/m3 of NO2. Total glutathione was significantly increased in blood by 24 h treatment with 9 or 18 mg/m3 of NO2, whereas blood oxidized glutathione was not affected. In lung tissue we observed only a significant increase of oxidized glutathione after 24 h of exposure to 9 and 18 mg/m3 of NO2. These data suggest that many biochemical and cellular parameters are altered after acute or subacute exposure to relatively high doses of NO2, especially in the first 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗
PubMed1994

Solubilization and characterization of d-fenfluramine binding sites from bovine cerebral cortex.

Stable d-Fenfluramine binding activity was obtained in high yields, in cholate extracts of bovine cerebral cortex crude membrane preparations. Dissociation constant (Kd 17 nM), stereoselectivity and the rank order of potencies of various serotonin uptake inhibitors were similar to those measured in native membranes. The inhibitory effect of Na+ ions was also maintained in the soluble state, since the presence of 100 mM Na+ leads to an even greater reduction of the binding than in membrane-associated binding sites. Photoaffinity labeling of soluble binding sites with p-[125I]d-Fenfluramine has led to the identification of a single specific band of molecular weight around 40-50 kDa. This suggests that d-Fenfluramine binding sites are separate molecular entities from the serotonin transporter, that belongs to a family of integral membrane proteins of 68-73 kDa molecular weight.

Affinity Labels↗
PubMed1994

An automated system for animal exposure to nitrogen dioxide.

We have designed an automated system for controlled exposure of rodents to nitrogen dioxide (NO2). The system consists of 1) two stainless-steel exposure chambers (3.96 m3), for control and treated animals, in which temperature, humidity, and air changes are consistent with current guidelines for rodent housing; 2) a cylinder containing 1% NO2 in N2; 3) a detector connected with a personal computer system that monitors the NO2 concentration, and regulates the NO2 influx, using a closed-loop feedback; and 4) a fan system to distribute the gas uniformly within the chambers. In a typical experiment rats were exposed to 15 ppm of NO2, and changes in the differential count of polymorphonuclear leukocytes, macrophages, and lymphocytes in bronchoalveolar lavage fluid were investigated.

Animals↗
PubMed1993

Molecular characteristics of a protease-resistant, amyloidogenic and neurotoxic peptide homologous to residues 106-126 of the prion protein.

In the prion-related encephalopathies the prion protein is converted to an altered form, known as PrPSc, that is partially resistant to protease digestion. This abnormal isoform accumulates in the brain and its protease-resistant core aggregates extracellularly into amyloid fibrils. We have investigated the conformational properties, aggregation behaviour and sensitivity to protease digestion of a synthetic peptide homologous to residues 106-126 of human PrP, which was previously found to form amyloid-like fibrils in vitro and displayed neurotoxic activity toward primary cultures of rat hippocampal neurons. A scrambled sequence of peptide PrP 106-126 was used as a control. By circular dichroism, PrP 106-126 exhibited a secondary structure composed largely of beta-sheet, whereas the scrambled sequence of PrP 106-126 showed a random coil structure. The beta-sheet content of PrP 106-126 was much higher in 200 mM phosphate buffer at pH 5.0 than in the same buffer at pH 7.0. Laser light scattering analysis showed that PrP 106-126 aggregated immediately after dissolution in 20 mM or 200 mM phosphate buffer, pH 5.0 and 7.0, whereas scrambled PrP 106-126 did not. PrP 106-126 aggregates had an average hydrodinamic diameter of 100 nm and an average molecular weight of 12 x 10(6) +/- 30% Daltons, corresponding to the aggregation of 6000 +/- 30% molecules. Peptide PrP 106-126 showed partial resistance to digestion with Proteinase K and Pronase, whereas scrambled PrP 106-126 was completely degraded by incubation with the enzymes at 37 degrees C for 30 minutes.

Amino Acid Sequence↗