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Biomedical subjects

R Barbieri

Publications and source records attributed to R Barbieri.

At least 91 records · Page 5Linked to original sources
PubMed1986

Human leukemic K562 cells: suppression of hemoglobin accumulation by a monoclonal antibody to human transferrin receptor.

The receptor for transferrin plays an important role both in tumor cell growth and in hemoglobin synthesis. In this paper, we demonstrate that the monoclonal antibody 42/6 to human transferrin receptor inhibits iron uptake in the human leukemic K562 cell line and suppresses hemoglobin accumulation in K562 cells induced to erythroid differentiation by butyric acid. In contrast, only slight inhibitory effects were observed on cell proliferation of both uninduced and erythroid-induced K562 cells treated with the 42/6 monoclonal antibody. In addition, the 42/6 monoclonal antibody to human transferrin receptor does not inhibit butyric acid-induced accumulation of gamma-globin mRNA. The effect of the 42/6 monoclonal antibody on hemoglobin synthesis appears to be restricted to human cell lines, as murine Friend erythroleukemic cells undergo erythroid differentiation when cultured in the presence of hexamethylenebisacetamide plus the 42/6 monoclonal antibody. The findings reported in this paper suggest (a) a dissociation of iron transport and accumulation of heme molecules from the expression of globin genes and (b) a different requirement of iron uptake by different iron-dependent functions such as cell proliferation and hemoglobin expression.

Antibodies, Monoclonal↗
PubMed1986

Identification of a c-myc oncogene lacking the exon 1 in the normal cells of a patient carrying a thyroid carcinoma.

In this paper we describe an alteration of the c-myc oncogene present in the white blood cells and normal as well as neoplastic thyroid cells of a subject carrying a thyroid carcinoma. Restriction enzyme mapping and hybridization to human c-myc probes specific for different regions of this gene demonstrate that this subject carries, in addition to the normal one, a c-myc oncogene lacking the first exon and part of the first intron. The levels of the c-myc mRNA in thyroid cells of this subject do not show differences with respect to thyroid cells from other subjects. Taken together, these findings indicate that the deletion of the first exon of the c-myc oncogene, in itself, does not produce overtranscription of this oncogene nor hematopoietic malignancies.

Base Sequence↗
PubMed1986

Lack of correlation between hypomethylation and expression of the HLA-DR alpha gene.

DNA methylation at the 5'-CCGG-3' sites of the HLA-DR alpha gene and relative flanking regions has been analyzed by Msp I and Hpa II enzymatic digestion in order to determine whether a correlation exists between DNA methylation and transcription of the HLA-DR alpha gene. Unexpectedly, and in contrast to the behavior of most eukaryotic genes, no positive correlation was found between hypomethylation and expression. In fact, HLA-DR alpha appears to be fully unmethylated at Msp I/Hpa II sites in K562 cells, not expressing DR molecules, and to exhibit a high degree of methylation in Colo 38 cells, which actively transcribe the gene. The unorthodox behavior of HLA-DR alpha is not unique to melanoma or erythroid cells since a similar, positive correlation between methylation and expression also exists when this analysis is extended to cell lines belonging to other histotypes.

Cell Line↗
PubMed1986

Methylation and expression of c-myc and c-abl oncogenes in human leukemic K562 cells before and after treatment with 5-azacytidine.

The correlation between expression and extent of DNA methylation of c-myc and c-abl oncogenes has been investigated in the human leukemic K-562 cell line before and after 5-azacytidine-mediated erythroid induction. RNA accumulation was analyzed by cytoplasmic dot hybridization and DNA methylation by using HpaII and MspI endonucleases, which differently cleave the CCGG sequence depending on cytosine methylation. Both the oncogenes are expressed in uninduced cells; however, whereas the c-myc expression does not change following 5-azacytidine treatment, the c-abl expression sharply decreases. The HpaII pattern shows that the c-myc DNA region is undermethylated and that the c-abl gene is hypermethylated both before and after the erythroid induction. Nevertheless, in both the genes 5-azacytidine produces variations in the MspI pattern compatible with mCmCGG to CmCGG demethylations.

Azacitidine↗
PubMed1985

The antitumor activity of di-n-butyltin(IV) glycylglycinate, and the correlation with the structure of dialkyltin(IV) glycylglycinates in solution studied by conductivity measurements and by infrared, nuclear magnetic resonance, and Mössbauer spectroscopic methods.

The in vivo activity of Bu2nSnGlyGly, Na(Cl2GaGlyGly), and ClGaGlyGly (GlyGly2- = glycylglycinate) has been investigated in connection with a number of tumors. Positive results have been obtained only for the Bu2nSnIV complex in the case of leukemia P-388. In order to try to interpret the pharmacological data on a molecular basis, the nature of the species present in solutions of AlK2Sn GlyGly complexes, as well as the reactivity of aqueous Me2SnGlyGly, have been studied. The presence of chelated species (I), Figure 1, in organic solvents, and the equilibrium (I) in equilibrium (II), Figure 1, in water and mixed water-organic solvent systems, have been inferred from conductance measurements, as well as from studies by Mössbauer (in frozen solution), 1H, 13C, and 119Sn NMR, and ir spectroscopy. Moreover, solvated (II) would release AlK2SnIV moieties, as evidenced by the slow formation of (Me2SnO)n from aqueous Me2Sn GlyGly. The involvement of (I) and (II) in the transportation of these drugs across cell membranes is discussed.

Animals↗
PubMed1985

beta (+)-Thalassaemia in the Po river delta region (northern Italy): genotype and beta globin synthesis.

Six beta(+)-thalassaemic patients from the Po river delta region have been studied. Using synthetic oligonucleotides as specific hybridisation probes, the beta(+) IVS I mutation (G----A at position 108) was demonstrated. This lesion and the enzyme polymorphism pattern in the subjects examined are the same as have been described for other Mediterranean beta(+)-thalassaemias. Antenatal diagnosis through DNA analysis of beta(+)-thalassaemia is therefore possible. The production of beta globin in a beta(+), homozygote and in a beta (+), beta(0) 39 (nonsense mutation at codon 39) double heterozygote is approximately 20% and 10% respectively of total non-alpha globin synthesis. Despite some overlapping of the results, similar beta globin synthesis levels have been obtained in 43 beta(+)-thalassaemia patients. This suggests that in the Po river delta region the most common thalassaemic genes are beta(0) 39 and beta(+) IVS I.

Autoradiography↗
PubMed1985

Gene deletion in an Italian haemophilia B subject.

DNA from 20 Italian haemophilia B patients was analysed by the Southern blotting technique and hybridisation to a factor IX cDNA probe. A large deletion of factor IX gene was detected in one patient with antibodies to the infused factor; the EcoRI pattern of the other 19 subjects examined was normal.

Chromosome Deletion↗
PubMed1984

Human leukemia K562 cells: relationship between hemin-mediated erythroid induction, cell proliferation and expression of c-abl and c-myc oncogenes.

We have studied the expression of the c-myc and c-abl oncogenes in two human leukemic K562 cell lines which do express hemoglobin genes retaining a differential rate of cell proliferation. Our data indicate that in hemin-induced K562(S) cells the expression of c-abl oncogene decreases and appears to be related to a decrease in the proliferation capacity rather than to the activation of differentiated functions. The K562(hC) cell line, which produces large amounts of Hb Gower 1 retaining an efficient rate of cell proliferation, expresses indeed the c-abl oncogene at high level.

Cell Division↗
PubMed1984

Human leukemic K562 cells: differential effects of 5-azacytidine on DNA methylation of epsilon-, gamma-globin and 7SL RNA genes.

5 Azacytidine ribonucleoside (5 Aza CR), greatly enhances erythroid differentiation of the K562(h) cell line, with a sharp increase of embryonic and fetal globin gene expression. This phenomenon is correlated with the undermethylation of gamma-globin but not of epsilon-globin, as the epsilon-globin gene is already extensively undermethylated before 5AzaCR induction. By contrast no variations in both DNA methylation and expression are observed in 7SL RNA genes.

Azacitidine↗
PubMed1984

Human leukemia K-562 cells: induction of erythroid differentiation by 5-azacytidine.

In this article we show that the cytidine analog 5-azacytidine is able to induce differentiation of the human leukemia K-562 cell line. Erythroid induction is associated with (a) an increase of the overall globin synthesis and globin mRNA accumulation, (b) a relative increase of fetal with respect to embryonic globins, and (c) a decrease of the proliferative capacity of hemoglobin-containing cells. In addition, we have analysed the DNA methylation pattern at the cleavage sites of MspI and HpaII restriction enzymes, which are known to cleave differently CCGG DNA sequences when 5-methylcytosine is present. These experiments indicate that in K-562 cells treated with 5-azacytidine, DNA becomes hypomethylated, suggesting that genetic programmes leading to an erythroid phenotype may be activated by a reduction of DNA methylation.

Azacitidine↗
PubMed1983

[Inhibition of heme biosynthesis in erythroid precursors (BFU-e) isolated from human peripheral blood: effects on globin synthesis].

We studied the relationship between heme accumulation and globin synthesis in human erythroid precursors which were stimulated by 2 I.U. of erythropoietin in semi-solid cultures (1% methyl-cellulose, 20% fetal calf serum) and treated with 6-9 micrograms/ml of desferrioxamina (DF), a potent inhibitor of heme synthesis (6). Heme accumulation was detected by specific reaction with benzidine (4), globin synthesis by CM-cellulose column chromatography. Our results demonstrate that globin gene expression occurs in DF-treated erythroid cells which do not accumulate heme molecules. As heme does affect translation and stability of globin mRNA (10) our system might be suitable for studies focused on pathological alterations of erythropoiesis associated with the presence of unstable globin mRNAs and/or unstable globins.

Chromatography, Ion Exchange↗
PubMed1983

Evidence of non-A, non-B hepatitis in children with acute leukemia and chronic liver disease.

Eleven children with acute lymphoblastic leukemia and chronic liver disease, who had negative reactions for hepatitis B virus markers in the liver, were studied at the time of therapy withdrawal for an antigen-antibody system linked to non-A, non-B (NANB) hepatitis infection. By immunofluorescence, six of the 11 children had a positive reaction for the NANB antigen in the liver, and five of these six children also had a positive reaction for the NANB antibody in serum. Histologic lesions were more severe in patients with the NANB antigen in the liver compared with those with a negative reaction.

Adolescent↗
PubMed1983

Selective culture of rat CNS neurons in a synthetic medium.

A Chemically Defined Medium is described which facilitates the survival of neurons in primary cultures of rat cerebral hemispheres. More than 90% of all cells were identified as neurons using neurofilament as a marker in an immunocytochemical assay. In contrast, serum-supplemented medium, by stimulating nonneuronal cell proliferation, hinders the survival of neurons in culture.

Animals↗
PubMed1981

Detection by immunofluorescence of an antigen-antibody system in patients with acute and chronic non-A, non-B hepatitis.

An antigen-antibody system has been identified by immunofluorescence in patients with non-A, non-B hepatitis. The non-A, non-B antigen was localized in the hepatocyte nuclei of liver biopsies from patients with acute post-transfusion or sporadic non-A, non-B hepatitis and in those from patients with chronic post-transfusion non-A, non-B hepatitis, the percentage of positive cells being most prominent in patients receiving immunosuppressive treatment. Absence of the antigen in normal livers and in livers from patients with type B hepatitis infection indicated its specific association with non-A, non-B infection. Antibody reacting with the nuclear antigen became detectable in serum during post-transfusion acute non-A, non-B hepatitis in 11 out of 15 cases; it was absent before transfusion. Six out of 12 cases of sporadic acute non-A, non-B hepatitis were also found to produce the antibody, which was repeatedly found to be absent during the acute phase in five patients with type A and in eight with type B hepatitis. The non-A, non-B antibody, mainly an IgM antibody, persisted in serum for prolonged periods of time after onset, both in patients showing biochemical resolution of their illness and in those who continued to have liver damage after the acute phase. Accordingly, eight out of nine patients with chronic non-A, non-B hepatitis were found positive for the antibody in serum, seven at the time the non-A, non-B antigen was detected in their liver. Thus this non-A, non-B associated antigen-antibody system shares remarkable similarities of behaviour with the "core" system of the hepatitis B virus.

Antibodies, Viral↗