Biomedical subjects

Amedeo Conti

Publications and source records attributed to Amedeo Conti.

24 records · Page 2Linked to original sources

PubMed2002

Characterization of plasma factors that alter the permeability to albumin within isolated glomeruli.

Focal segmental glomerulosclerosis (FSGS) is responsible for intractable proteinuria and has become the leading cause of renal insufficiency in children. Protenuria in FSGS is probably due to the effect of one or more permeability plasma factors which increase the glomerular permeability to proteins. We fractioned serum from children with FSGS using two mixed chromatographic-electrophoretic approaches and have purified ten proteins among several hundreds which maintained the original permeability activity after renaturation, utilizing an isolated rat glomeruli assay. Six proteins were successfully characterized by mass spectometry as fibulin, apolipoprotein J, vitronectin, albumin isoforms, gamma chain fibrinogen and mannan-binding lectin-associated serine protease. Both procedures utilized for purification were based on affinity chromatography with Protein A-Sepharose and ended with two-dimensional electrophoresis, whereas the intermediate steps were different. Cross inhibition with zinc and aprotinin of purified factors and whole FSGS serum indicate strong homology. These are the first data demonstrating permeability activity for serum proteins, an observation with important implications in pathogenesis of proteinuria. Determination of the serum levels of each protein and a careful differentiation of FSGS from normal serum could provide the basis for clarifying the mechanism of proteinuria.

Adolescent↗

PubMed2002

A proteomic approach to evaluate the butyrophilin gene family expression in human milk fat globule membrane.

Human butyrophilin (BTN) expression in milk fat globule (MFGM) was evaluated using two dimensional electrophoresis (2-DE) as the separation technique, and peptide mass mapping by matrix-assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) as the identification tool. Since milk composition changes throughout lactation time, 2-DE maps in the pH range 4-7 of colostral MFGM and mature MFGM were compared, showing only slight differences in BTN spot distribution. The BTN gene family codes for seven proteins (BTN, BTN2A1, BTN2A2, BTN2A3, BTN3A1, BTN3A2, BTN3A3), their presence in human tissues has to date been evaluated only at a transcriptional level. Among 70 spots, analyzed and identified by MALDI-MS, 13 spots were identified as BTN spots and only one as a fragment of BTN2A1. BTN was present in multiple glycoforms, and two smaller BTN forms of about 45 kDa were also identified. We propose an array of BTNs on human MFGM, which could provide breast-fed infants with immune molecules during the neonatal period.

Amino Acid Sequence↗

PubMed2002

Cloning and characterization of two catechol 1,2-dioxygenase genes from Acinetobacter radioresistens S13.

Two novel catechol 1,2-dioxygenase (C 1,2-O) genes have been isolated from an Acinetobacter radioresistens strain that grows on phenol or benzoate as sole carbon and energy source. Designated as catA(A) and catA(B), they encode proteins composed of 314 and 306 amino acids, whose deduced sequences indicate that they have approximately 53% identity, whereas their NH2-terminal and COOH-terminal regions have no sequences in common. This may explain their different thermal and pH stability. Polyclonal antibodies raised against an amino-terminal CatA(A) peptide or the whole CatA(B) protein were used to establish their inducible and differential expression patterns upon bacterial growth in phenol or benzoate. The CatA(A) protein (IsoA) was induced by both phenol and benzoate though with different kinetics, whereas the catA(B) product (IsoB) was constitutively produced at low levels that increased only during growth in the presence of benzoate.

Acinetobacter↗

PubMed2002

Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results.

BACKGROUND: The hazelnut major allergens identified to date are an 18-kd protein homologous to Bet v 1 and a 14-kd allergen homologous to Bet v 2. No studies have reported hazelnut allergens recognized in patients with positive double-blind, placebo-controlled food challenge (DBPCFC) results or in patients allergic to hazelnut but not to birch. OBJECTIVE: We characterized the hazelnut allergens by studying the IgE reactivity of 65 patients with positive DBPCFC results and 7 patients with severe anaphylaxis to hazelnut. METHODS: Hazelnut allergens were identified by means of SDS-PAGE and IgE immunoblotting. Further characterization was done with amino acid sequencing, evaluation of the IgE-binding properties of raw and roasted hazelnut with enzyme allergosorbent test inhibition, assessment of cross-reactivity with different allergens by means of immunoblotting inhibition, and purification by means of HPLC. RESULTS: All the sera from the patients with positive DBPCFC results recognized an 18- and a 47-kd allergen; other major allergens were at molecular weights of 32 and 35 kd. Binding to the 18-kd band was inhibited by birch extract, indicating its homology with the birch major allergen, and abolished in roasted hazelnut. The 47-kd allergen is a sucrose-binding protein, the 35-kd allergen is a legumin, and the 32-kd allergen is a 2S albumin. Patients with severe anaphylactic reactions to hazelnut showed specific IgE reactivity to a 9-kd allergen, totally inhibited by purified peach lipid-transfer protein (LTP), which was heat stable and, when purified, corresponded to an LTP. CONCLUSIONS: The major allergen of hazelnut is an 18-kd protein homologous to Bet v 1, and the 9-kd allergen is presumably an LTP. Other major allergens have molecular weights of 47, 32, and 35 kd.

Allergens↗

PubMed2002

Hypersensitivity to mugwort (Artemisia vulgaris) in patients with peach allergy is due to a common lipid transfer protein allergen and is often without clinical expression.

BACKGROUND: The observation of mugwort-specific IgE antibodies in patients with peach allergy suggests that mugwort sensitization might play a role in sensitization to peach. OBJECTIVE: We sought to study the clinical manifestations of mugwort hypersensitivity in patients with peach allergy, identify the common allergens, and evaluate their IgE crossreactivity. METHODS: Patients with oral allergy syndrome for peach and specific IgE antibodies to mugwort were investigated for respiratory symptoms during the mugwort season. Peach and mugwort allergens were identified by means of SDS-PAGE and IgE immunoblotting. Immunoblotting inhibition experiments were done to study cross-reactivity between peach and mugwort and other pollens. RESULTS: Seventeen patients were studied, 10 with no seasonal respiratory symptoms and 7 with clear late summer respiratory symptoms. In IgE immunoblotting the 10 asymptomatic patients reacted only to a 9-kd allergen of both mugwort and peach, whereas the 7 patients with pollinosis reacted to other allergens. Ten patients with mugwort allergy, no history of allergy to peach, and negative results for peach-specific IgE antibodies were also studied. The mugwort 9-kd protein was identified as a lipid transfer protein (LTP) homologous to peach LTP. Immunoblotting inhibition showed that IgE binding to the peach 9-kd band was totally inhibited by 4 microg of peach LTP but only by 400 microg of mugwort LTP, whereas 4 microg of both mugwort and peach LTP totally inhibited the mugwort immunoblotting. The results were similar with other pollens. CONCLUSIONS: Patients sensitized only to the 9-kd LTP of mugwort do not present hay fever symptoms, and this sensitization is a consequence of the peach sensitization.

Adolescent↗

PubMed2001

Integrin-induced epidermal growth factor (EGF) receptor activation requires c-Src and p130Cas and leads to phosphorylation of specific EGF receptor tyrosines.

Integrin-mediated cell adhesion cooperates with growth factor receptors in the control of cell proliferation, cell survival, and cell migration. One mechanism to explain these synergistic effects is the ability of integrins to induce phosphorylation of growth factor receptors, for instance the epidermal growth factor (EGF) receptor. Here we define some aspects of the molecular mechanisms regulating integrin-dependent EGF receptor phosphorylation. We show that in the early phases of cell adhesion integrins associate with EGF receptors on the cell membrane in a macromolecular complex including the adaptor protein p130Cas and the c-Src kinase, the latter being required for adhesion-dependent assembly of the macromolecular complex. We also show that the integrin cytoplasmic tail, c-Src kinase, and the p130Cas adaptor protein are required for phosphorylation of EGF receptor in response to integrin-mediated adhesion. We show that integrins induce phosphorylation of EGF receptor on tyrosine residues 845, 1068, 1086, and 1173, but not on residue 1148, a major site of phosphorylation in response to EGF. In addition we find that integrin-mediated adhesion increases the amount of EGF receptor expressed on the cell surface. Therefore these data indicate that integrin-mediated adhesion induces assembly of a macromolecular complex containing c-Src and p130Cas and leads to phosphorylation of specific EGF receptor tyrosine residues.

CSK Tyrosine-Protein Kinase↗