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Biomedical subjects

A Sabbatini

Publications and source records attributed to A Sabbatini.

At least 37 records · Page 2Linked to original sources
PubMed1995

Expression of multidrug resistance (mdr) gene(s) in primary lymphoid organs of chicken immune system during embryonic development.

The presence of a multidrug resistance (MDR) related protein, P-170, in normal and pathological lymphoid cells has been described. The present report evaluates the expression of the mdr 1 gene by using the reverse Polymerase Chain Reaction (PCR) on cells obtained from the thymus and bursa of chicken embryos starting from day 12 until hatching. Results show that the thymic cells are positive from day 12 to the end of the observation period. In contrast, mdr mRNA was detected in the bursa from day 14 to day 17 of embryonic life. Possible relationships between the expression of mdr and the development of T and B lymphocytes are discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Binding of GC (VDBP) to membranes of human B lymphocytes following stripping of extant protein.

The presence of Gc (vitamin D binding protein) has been consistently demonstrated on the membrane of B lymphocytes. This protein appears to be spatially associated with surface immunoglobulins. The origin of this surface protein has not yet been determined and the purpose of the present paper was to investigate if Gc may bind to human lymphocytes after immunoglobulin (Ig) capping. For this purpose the presence of Gc on B lymphocytes was examined by three different approaches. First, when cells were examined by immunofluorescence and quantified by flow cytometry, membrane Ig capping was followed by a dramatic decrease in positivity for Gc when compared to native cells. In addition, incubation of capped cells with purified Gc was followed by a significant increase in fluorescence, indicating that this protein had been able to bind again. Second, analysis of solubilized lymphocytes by Western blotting showed that native lymphocytes and capped cells incubated with purified Gc contained a large quantity of a 56kDa protein which was immunoreactive with anti Gc antibodies. This protein band was much weaker on blots from capped cells not treated with Gc. Third, radiobinding assays indicated that, following capping, cells were able to bind Gc in saturable fashion. These results suggest that membrane Gc could play a role in the entry of vitamin D metabolites into lymphocytes.

B-Lymphocytes↗
PubMed1994

Functional analysis of two tetanus toxin universal T cell epitopes in their interaction with DR1101 and DR1104 alleles.

In this study we have investigated the interaction between two DR11 alleles (DB*1101 and DB*1104) and two previously described tetanus toxin (tt) universal T cell epitopes P2(tt830-843) and P30(tt947-967) by means of a functional cytotoxic competition assay. Both truncation analysis and single alanine substitution analysis were performed. In addition, the capacity of truncated and single alanine substituted peptides to be recognized by human T cell clones from donors bearing the DR1101 or DR1104 alleles was assessed. In the case of truncated peptides the same binding and recognition pattern was observed with both alleles. Longer peptides were better competitors and more potent stimulators, a result that should be taken into account when these peptides are used as immunogens. None of the single alanine substitutions could abrogate or strongly diminish the inhibitory capacity of the analogues tested indicating the lack of strong "anchor residues" present in P2 and P30 and implicated in DR binding. In addition, although the original peptide sequences were presented to specific T cell clones with comparable efficiency, some of the alanine single substituted peptides were better recognized in association with one of the alleles by clones derived from individuals bearing the homologous allele. The only exception was the tt951-967 analogue ttW955A, which was preferentially recognized in association with the DR1104 allele regardless of the clone tested. This suggests that, although it binds to both alleles with comparable efficiency, the MHC-peptide complex so formed is conformationally distinguishable by specific T cell clones.

Alleles↗
PubMed1994

Immune response to different sequences of the EBNA I molecule in Epstein-Barr virus-related disorders and in autoimmune diseases.

Epstein-Barr virus (EBV) infection is associated with production of autoantibodies. The N-terminal 35-58 sequence of EBNA I, one of the nuclear antigens encoded by EBV, is highly homologous to the C-terminal 95-119 region of the ribonucleoprotein SmD. Autoantibodies specific for SmD are present only in systemic lupus (SLE) sera and are therefore considered a serological marker of SLE. We measured antibodies to the EBNA I 35-58 sequence in EBV-related diseases and in autoimmune disorders. Antibodies to the EBNA I 35-58 peptide were present in 30% of normal sera, 12% Burkitt lymphoma, 22% infectious mononucleosis, 25% rheumatoid arthritis, 38% SLE and 33% Sjogren's syndrome. Antibodies to the SmD 95-119 peptide were detectable in 32% of SLE sera, 17% infectious mononucleosis and 12% Burkitt lymphoma. The specificity of anti-EBNA I 35-58 antibodies affinity-purified from nine sera was analysed by means of an inhibition assay. Only anti-EBNA I 35-58 antibodies affinity-purified from SLE sera have a similar affinity for the viral peptide and the SmD C-terminal one; they also bind the recombinant SmD in western blot. The results indicate that antibodies to EBNA I 35-58 are produced in normals, in EBV-related diseases and in autoimmune disorder, but only SLE sera contain anti-viral antibodies cross-reactive with an autoantigen.

Amino Acid Sequence↗
PubMed1994

Differential modulation of P-glycoprotein expression by dexamethasone and 3-methylcholanthrene in rat hepatocyte primary cultures.

Spontaneous and culture condition-dependent changes in P-glycoprotein expression and activity have been monitored in primary cultures of rat hepatocytes by using immunoblotting, PCR and fluorimetric techniques. In hepatocytes cultured in basal medium without addition of dexamethasone or 3-methylcholanthrene, mdr mRNA and P-glycoprotein increased progressively throughout a 72 h culture period, in concert with an enhancement in the ability to extrude the fluorescent dye Rhodamine-123. Addition of 1 microM dexamethasone to the culture medium slowed down the increase in mdr mRNA and P-glycoprotein, while inducing a significant increase in the efficiency of R-123 efflux. Addition of either 100 nM or 10 microM DEX produced different changes in mdr mRNA and protein, unrelated to the rate of Rhodamine-123 extrusion. When 50 microM 3-methylcholanthrene was added to the culture medium in the absence of any hormone supplementation, no significant changes in P-glycoprotein activity and expression took place, in comparison with control cultures. On the contrary, in the presence of dexamethasone (100 nM and 1 microM), 3-methylcholanthrene induced an increase in mdr mRNA and in the amount of immunoblottable protein during culture, without producing any concomitant increase in the efficiency to extrude Rhodamine-123. The last phenomenon resulted to be an artefact, since 3-methylcholanthrene was shown to inhibit Rhodamine-123 transport competitively. These results indicate that rat hepatocyte P-glycoprotein may be variously modulated in vitro, by supplementing culture medium with hormones and/or xenobiotics. Functional activity of the P-glycoprotein is not necessarily related with protein amount and/or mdr RNA.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Autoantibodies from mixed cryoglobulinaemia patients bind glomerular antigens.

Mixed cryoglobulinaemia (MC) is a disorder characterized by the presence of large amounts of cryoprecipitating IgM-IgG complexes. An immune complex glomerulonephritis develops in one third of all patients, but its occurrence does not seem related to the amount of cryoglobulins in the sera, nor to their complement-fixing ability. In this study we investigated the presence of IgG antibodies reactive with kidney antigens in 33 MC patients (11 with glomerulonephritis, 22 without renal involvement). A total glomerular extract was run on a 10% acrylamide gel, blotted to nitrocellulose and probed with the patients' sera. Sera from half of the patients without renal involvement reacted with several glomerular antigens whose molecular weight ranged between 200 and 29 kD. In the group with renal involvement, sera from 7/11 patients reacted with an antigen of 50 kD, which is also expressed in thymus, but not in the heart or liver. In a follow-up study of four patients with renal involvement, the amount of serum antibody specific for the 50-kD antigen fluctuated, either spontaneously or in response to therapy. These results show that antibodies specific for glomerular antigens are detectable in MC sera. The immune response against a 50-kD antigen expressed in the kidney and thymus seems to be restricted to a subset of MC patients with renal involvement. Circulating autoantibodies specific for glomerular antigens might contribute to the induction of glomerulonephritis in MC forming immune complexes in situ.

Antibody Specificity↗
PubMed1994

[Congenital cyst of the choledochus. A case report and review of the literature].

Congenital cysts of the choledochus and of the glandulae mucosae biliosae are rare anomalies generally observed in pediatric age: it is in fact exceptional to detect them in adults. There seems also to be a difference in the occurrence among the various races since the disease is more frequently seen in the Japanese and in women. In the Western world the incidence of this pathology has rated to be 1 out of 26,000 hospitalizations, consequently the personal experience and familiarity of every surgeon with this disease will be naturally limited. The authors describe the case of a women, aged 21, under observation as carrier of cystoduodenostomy after congenital cyst of the choledochus. A calculosis of the common hepatic duct as well as the stenosis of the previous cystoduodenostomy are also discovered. The abscission of the cyst and the confection of a Roux's en Y loop hepaticojejunostomy with the separation of the previous gastrojejunostomy are then performed. According to the authors, the complete abscission of the cyst and the Roux hepaticojejunostomy should be considered the surgery of choice when the local situation and the patient's general condition allow it because this treatment reduces the occurrence of late postoperative accidents such as lithiasis and cholangitis and the possibility of malignant degeneration of the cyst. Two years after the operation, the patient is in excellent health conditions.

Adult↗
PubMed1993

Vitamin D binding protein is produced by human monocytes.

The expression of the DBP (vitamin D binding protein) gene was investigated in monocytes and in peripheral blood lymphocytes. DBP message was amplified through 35 cycles of PCR amplification using specific oligonucleotide primers. PCR products of the expected size were further identified by Southern blotting using a specific DBP probe. No expression of the DBP gene could be detected in peripheral blood lymphocytes, nor in the monocyte-derived U 937 cell line. In contrast, message for DBP was identified in monocytes activated with lipopolysaccharide when analyzed between 6 and 10 h following stimulation. These results suggest that the temporal expression of the DBP gene could play a major role in the activation of monocytes by 1-25(OH)2D3.

Base Sequence↗
PubMed1993

Autoantibodies from patients with systemic lupus erythematosus bind a shared sequence of SmD and Epstein-Barr virus-encoded nuclear antigen EBNA I.

SmD is one of the small nuclear ribonucleoproteins frequently targeted by autoantibodies in systemic lupus erythematosus. We isolated and characterized the antibodies present in lupus sera that are specific for the C-terminal region of SmD (sequence 95-119). This region is highly homologous to sequence 35-58 of the EBNA I antigen, one of the nuclear antigens induced by infection with Epstein-Barr virus. Antibodies affinity purified over a peptide 95-119 column were able to recognize this sequence in the context of the whole SmD molecule, as they reacted with blotted recombinant SmD. Anti-SmD 95-119 antibodies bound also the EBNA I 35-58 peptide and detected the EBNA I molecule in a total cell extract from Epstein-Barr virus-infected lines. A population of anti-SmD antibodies is, therefore, able to bind an epitope shared by the autoantigen and the viral antigen EBNA I. To investigate the involvement of this shared epitope in the generation of anti-SmD antibodies, we immunized mice with the EBNA I 35-58 peptide. Sera from immunized animals displayed the same pattern of reactivity of spontaneously produced anti-SmD antibodies. They reacted in fact with the EBNA peptide as well as with SmD 95-119 and recombinant SmD. These data suggest that molecular mimicry may play a role in the induction of anti-SmD autoantibodies.

Amino Acid Sequence↗
PubMed1993

Is binding of vitamin D binding protein related to cell differentiation?

Vitamin D binding protein (Gc) is present on the surface of several blood cells and may interfere with the activity of 1,25(OH)2D3. It has previously been reported that Gc may bind to the U-937 line which is known to differentiate upon exposition to 1,25(OH)2D3. In the present paper, we evaluate the expression of Gc on the surface of U-937 and HL-60 lines. Both cell lines did not express Gc on their surface but U-937 cells were able to bind human purified Gc added to the medium whereas HL-60 were not. After culturing with 1,25(OH)2D3, HL-60 became able to bind Gc. This property seems to be related to the monocytic differentiation induced by 1,25(OH)2D3. Conversely, when present together, 1,25(OH)2D3 reduces binding on U-937.

Calcitriol↗
PubMed1993

MHC class I H-2Kd-restricted antigenic peptides: additional constraints for the binding motif.

The previously defined binding motif of MHC class I H-2Kd-restricted antigenic peptides consists of a Y residue in position P2 and a hydrophobic residue with a large aliphatic side chain (L, I, or V) in position P9/P10 of optimal 9- or 10-mer peptides. We show now that the presence of a charged or a F residue in position P5 reduces the Kd-restricted competitor activity of several cytotoxic T lymphocyte (CTL) epitopes and model peptides, at a degree comparable to A substitutions for the P2 or the P9/P10 anchor residues. Various charged, polar, aromatic, and aliphatic amino acids were substituted for S256 in the CTL epitope Plasmodium berghei circumsporozoite (CS) 253-260 8-mer and in its CS 252-260 9-mer form, whereas a more restricted panel of substitutions was tested in the CTL epitopes influenza nucleoprotein 147-155 9-mer and HLA-CW3 170-179 10-mer. Analysis of all the Kd-restricted epitopes so far defined also revealed an uncharged residue at this position. These additional structural constraints present in the Kd binding motif may thus improve the prediction of new epitopes recognized by T cells in the context of this MHC molecule.

Amino Acid Sequence↗
PubMed1993

Reversing of chlorambucil resistance by ethacrynic acid in a B-CLL patient.

We evaluated the reversing activity of ethacrynic acid in a B-CLL patient resistant to chlorambucil. The glutathione S-transferase (GST) activity, measured in peripheral blood lymphocytes, resulted extremely elevated. Ethacrynic acid, at pharmacological concentrations, partially reversed chlorambucil resistance and this result appeared related to the increased GST levels.

Aged↗
PubMed1993

Vitamin D3 administration and multidrug resistance in acute nonlymphoblastic leukemia.

This article reports preliminary results from a pilot study started in 1986 on patients with acute myeloblastic leukemia treated for several months with low-dose arabinosylcytosine and 1(OH)D3. During treatment or at the time of relapse, a monoblastic component was frequently found. A high percentage of patients were P-170-positive. In 2 patients it was possible to show that blasts, previously P-170-negative, became positive after treatment. In these 2 patients, failure of clinical response to antileukemic therapy was associated with this phenotype. The addition of the revertant drug nicardipine to the previously inactive treatment induced a partial response. Thus, previously reported in vitro observations on the differentiating activity of vitamin D3 metabolites, possible induction of multidrug chemoresistance by differentiating agents and the revertant activity of the Ca++ antagonist nicardipine appear to be confirmed in vivo in the reported patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Mapping of epitopes on the SmD molecule: the use of multiple antigen peptides to measure autoantibodies in systemic lupus erythematosus.

Autoantibodies against the ribonucleoproteins B, B' and D are a serological marker of systemic lupus erythematosus (SLE). We mapped the epitopes recognized by autoantibodies on the SmD molecule by means of 7 synthetic peptides corresponding to the entire length of the protein. By ELISA assay, 25% of the lupus sera contained IgG antibodies specific for the C-terminal SmD sequence 95-119. This reactivity was confirmed by synthesizing the sequence as a multiple antigen peptide (MAP): antibodies reactive with the MAP 95-119 were present only in SLE and not in other connective tissue disorders. Sera containing high titers of anti-MAP 95-119 antibodies reacted in immunoblot with the SmD protein. These results indicate the presence of a dominant epitope in the C-terminal region of SmD, which is highly homologous to the Epstein-Barr virus induced nuclear protein EBNA I.

Amino Acid Sequence↗
PubMed1988

[Spontaneous pneumothorax: surgical aspects].

The authors illustrate the cases of spontaneous pneumothorax observed in their institute along with the diagnostic and therapeutic aspects. In accord with the experience of others as reported in the literature, they stress the importance of a precise, immediate diagnosis for the purposes of adopting the treatment of choice: in the presence of closed, partial forms a conservative approach is to be preferred, whereas in open and/or hypertensive cases an aspirative thoracic drainage must be provided without delay. Aggressive surgical treatment, with resection of the bullous lesions responsible for bronchopleural fistulas, will resolve the condition and should be implemented after a reasonable waiting period with aspirative drainage, or even, electively, in the first instance, in the presence of multiple relapses. In any event, the authors stress the need to avoid uncertainty and delay in view of the youthful age of most of the subjects affected and the potential danger of the complications of this apparently banal disease.

Age Factors↗
PubMed1987

[Primary lymphomas of the gastro-intestinal tract].

The authors considered a series of 13 patients undergone surgical operation for primary malignant lymphoma of digestive system, with gastric, gastro-jejunal, jejunal, ileal and colic localization. They examined diagnostic and therapeutic features and the follow-up data. According to literature, the authors remark the importance of roentgenology and endoscopy, that together with bioptic data may reach a definite and early diagnosis; an elective and wide surgical exeresis seems useful in early stages, showing a better prognosis and epithelial malignancies. IV stage patients, however, had a very poor survival; a quick management appears today the only factor affecting long-term results in these patients.

Adult↗