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Biomedical subjects

M Petrini

Publications and source records attributed to M Petrini.

At least 109 records · Page 6Linked to original sources
PubMed1986

Expression of cellular oncogenes in primary cells from human acute leukemias.

The structure and the expression of 11 cellular oncogenes (protooncogenes) were analyzed in primary cells from 20 acute lymphocytic (ALL) and 31 acute myelogenous (AML) leukemia patients. Neoplastic cells, obtained prior to initiation of therapy, were purified and classified, on the basis of both surface antigen pattern and morphology, into pre-B, B, and T ALL and M1-M5 AML. RNA was extracted and analyzed for expression of cellular oncogenes coding for nuclear proteins (c-myc, c-myb, c-fos), the beta-chain of platelet-derived growth factor (c-sis), growth factor receptors or related proteins (c-src, c-abl, c-fes, c-erbB), or putative intermediate transducers of mitogenic signals (c-Ha-ras, c-Ki-ras, c-N-ras). Quantitative analysis of total RNA was carried out by dot blot hybridization to specific cDNA or genomic probes. Number and size of transcripts were evaluated by blot hybridization of electrophoretically fractionated poly(A)+ RNA. Expression of c-myc and c-myb was detected in all leukemic cells at variable levels and was characterized by well-defined patterns within ALL subtypes. Conversely, significant levels of c-fos transcripts were detected only in myelomonocytic (M4) and monocytic (M5) leukemias. Among the "src-family," c-fes was expressed more in AML than ALL, and c-abl was expressed at variable but not elevated levels in all leukemia types. c-Ha-ras was uniformly expressed at low levels, as in non-neoplastic cells. c-Ki-ras transcription was detected only in T ALL; N-ras expression was barely demonstrable. The structure of these protooncogenes was not grossly modified, as evaluated by Southern analysis, except for c-myc rearrangement in B ALL. These studies indicate that cellular oncogene expression in specific subtypes of leukemic cells may relate to either the proliferative activity (c-myc, c-myb) or the differentiation state (c-fos) of the cells, or possibly to expression of receptors for putative hemopoiesis-related growth factors (c-fes, c-abl). Our data provide a basis for in-depth analysis of protooncogene expression in normal and neoplastic hemopoiesis.

DNA, Neoplasm↗
PubMed1985

Structural studies of T lymphocyte Fc receptors. Association of Gc protein with IgG binding to Fc gamma.

To obtain further information concerning the structure of Fc IgG-binding sites on human peripheral blood lymphocytes, enriched T-cells were surface-radioiodinated and treated with nonionic detergent, and the soluble supernatant was submitted to affinity chromatography selecting for components binding complexed IgG. Analysis of eluted material by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing, and two-dimensional electrophoresis demonstrated the major proteins to be of Mr 56,000, pI 4.8-5.1 and Mr 60,000, pI 5.0-5.6, and these were radiolabeled, indicating an origin in part from the T-cell membrane. While the Mr 56,000 band gave positive reactions upon transblotting with antisera to Gc protein, the identity of the Mr 60,000 protein remains unknown. Three other components were detected, although with less consistency; Mr 78,000, 42,000, and 20,000-25,000, respectively. Immunocytochemical experiments showed that less than 5% freshly isolated native T-cells were positive with antiserum to human Gc, but, after IgG antibody-coated erythrocyte rosetting, the number of positive cells increased to 15-25%, in close agreement with the percentage of IgG antibody-coated erythrocyte rosette-positive T-cells. These findings therefore indicate that, in addition to interaction with components of Mr 60,000, 42,000, and 20,000-25,000, complexed IgG binding to Fc gamma of human peripheral blood T-cells also becomes spatially associated with Gc protein.

Chromatography, Affinity↗
PubMed1985

Acquired spontaneous cytotoxicity of K562 in a subpopulation of monocytes.

Human peripheral blood monocytes were placed on a discontinuous density gradient of bovine serum albumin and fractionated into five subpopulations. Cells from each subpopulation were assayed for spontaneous cytotoxic activity against K562 tumor cells. Immediately following fractionation, monocytes were not cytotoxic. Following incubation for at least 48 hr, monocytes from two layers of the gradients clearly exhibited greater spontaneous cytotoxic activity than all others. The degree of cytotoxicity expressed by cells of these layers was enhanced by the addition of indomethacin and inhibited by prostaglandin E2 (PGE2). Monocytes acquiring spontaneous cytotoxicity did not secrete measurable levels of PGE2 and had increased levels of purine nucleoside phosphorylase after 72 hs of culture in vitro. Surface markers HNK-1 and Mac-1 normally associated with cytotoxic function, were detected on these cells by indirect immunofluorescence at isolation and after culture. The fraction with the greatest cytotoxic activity showed an increase in the proportion of cells displaying reactivity to HNK-1 after culture compared to initial isolation.

Antigens, Surface↗
PubMed1985

Modifications in the phagocytosis of human neutrophils induced by vinblastine and cytochalasin B: the effects of lithium.

The effects of lithium on the microtubular and microfilament systems of neutrophil granulocytes is described. The phagocytic capacity of human neutrophils was reduced or inhibited by using vinblastine or cytochalasin B. Lithium at concentrations ranging from 0.5 to 2.0 mEq/l proved to be capable of antagonising the action of vinblastine, whereas the action of cytochalasin B was found to be unaffected by lithium. Based on the antagonising effect of lithium on vinblastine-induced inhibition of phagocytosis, it is suggested that lithium acts--at therapeutically achievable levels--on the microtubular system of neutrophils, possibly through modulation of cyclic AMP levels.

Cytochalasin B↗
PubMed1984

Heterocellular hereditary persistence of fetal hemoglobin (HPFH). Molecular mechanisms of abnormal gamma-gene expression in association with beta thalassemia and linkage relationship with the beta-globin gene cluster.

We report a study of four families of Italian origin in which heterocellular HPFH is inherited linked to beta thalassemia over two or three generations. The HPFH + beta thalassemia carriers showed thalassemic blood pictures and elevated HbF and F-cell number without increase in the HbF/F-cell content. Association of this gene complex with a second beta thalassemia trait gives rise to a mild clinical picture characterized by 9-12 g/dl of mainly HbF in peripheral blood and no transfusion requirement. In two families, independent segregation of the HPFH or beta-thal trait was observed, and in one case the study of the DNA polymorphisms within the gamma delta beta gene cluster indicated that the HPFH mutation lies outside that DNA region. In one family the coexistence of a polymorphic variant of the A gamma chain (the A gamma T chain) allowed us to demonstrate that the increased gamma chain synthesis caused by the heterocellular HPFH determinant is directed by both chromosomes.

Adolescent↗
PubMed1984

The role of PNP enzyme in autologous rosette-forming cells.

Since purine nucleoside phosphorylase has been associated with suppressor function in lymphocytes, enzyme activities were studied in autologous rosette-forming cells, a subset showing suppressor properties. Levels of this enzyme were higher in these cells than in other T cells. Con A induction of autologous red cell receptors and suppressor activity of T cells were both inhibited in dose-dependent fashion by Formycin B, a well known inhibitor of purine nucleoside phosphorylase. Inhibition of autologous rosette-forming cells was obtained after pulse treatment of cells with Formycin B for as little as 1 hr, whereas cell proliferation was only inhibited when Formycin B was present throughout culture; this confirms the independence of cell proliferation, and development of red cell receptors and suppressor activity. This study indicates a crucial role for purine nucleoside phosphorylase enzyme in induction of T cell suppressor activity.

Concanavalin A↗
PubMed1984

Gc (vitamin D binding protein) binds to cytoplasm of all human lymphocytes and is expressed on B-cell membranes.

Peripheral blood lymphocytes were examined immunohistologically for evidence of interactions with Gc protein, a major vitamin D binding protein in serum. In the cytoplasm, binding sites for purified Gc were readily detectable in all cells, and these sites were only partially occupied by Gc. In contrast, on the membrane of viable cells, there was negligible evidence of binding of either the apo- or holoform of Gc protein, but substantial quantities of firmly bound immunoreactive endogenous Gc were detected. Separation experiments and double-label fluorescence with antisera recognizing defined phenotypic markers showed immunoreactive membrane Gc on 30-40% of unfractionated mononuclear cells and greater than 95% of monocytes or B cells. Only 5-8% of T cells were similarly reactive; these were not apparently confined to any given subset. Extraction of unfractionated cells with 6 M urea or solubilization in Nonidet P-40 released immunoreactive Gc protein, with physicochemical properties indistinguishable from those of Gc purified from serum (apparent MW 56K; pI 4.8-5.1). These findings indicate that membrane Gc may represent another surface immunofluorescence marker for B cells, and may play a role in immunocyte function.

B-Lymphocytes↗
PubMed1984

Role of autorosette forming cells in antibody synthesis in vitro: suppressive activity of ARFC in humoral immune response.

The role of autologous rosette forming cells (ARFC) in humoral immune responses was studied using an in vitro system. While depletion of ARFCs from PBL resulted in a significant increase of either total IgG or anti-TT IgG, addition of these cells to the system decreased the production of immunoglobulin to a level comparable to that of unfractionated PBL. The majority of the ARFCs reacted with anti-Leu2a and anti-Leu8. In contrast, the majority of non-ARFCs reacted with Leu3a and only 10% with Leu8 monoclonal antibodies. Stimulation of unfractionated PBL with concanavalin A (ConA) resulted in an increase of the ARFC population. ConA stimulation also increased the number of cells reactive with anti-Leu2 and/or anti-Leu8. The autorosette population had a higher purine nucleoside phosphorylase (PNP) content than the non-ARFC population. Although the ARFC suppressed synthesis of antibody by B cell in vitro when they were mixed with either autologous or allogeneic B cells, a marked proliferation of non-B cells was evident. We conclude that at least two different subpopulations of T cells are capable of forming rosettes with autologous red blood cells.

Antibodies, Monoclonal↗
PubMed1984

Embryonic----Fetal Hb switch in humans: studies on erythroid bursts generated by embryonic progenitors from yolk sac and liver.

The synthesis of embryonic (zeta, epsilon), fetal (alpha, gamma), and adult (beta) globin was evaluated in human yolk sacs (YS) and livers at different ontogenic stages (i.e., from 6 through 10-12 wk of age) by means of analytical isoelectric focusing. Globin production was comparatively evaluated in vivo (i.e., in directly labeled erythroblasts from YS and liver) and in vitro [i.e., in erythroid bursts generated in culture by erythroid burst-forming units (BFU-E) from the same erythropoietic tissues]. Erythroid bursts generated in vitro by BFU-E from 6-wk livers and YS show essentially a "fetal" globin synthetic pattern: this is in sharp contrast to the "embryonic" pattern in corresponding liver and YS erythroblasts directly labeled in vivo. The invitro phenomenon suggests that (i) 6-wk BFU-E constitute a new generation of progenitors, which have already switched from an embryonic to a fetal program, and/or (ii) expression of their fetal program is induced by unknown in vitro factor(s), which may underlie the in vivo switch at later ontogenic stages. It is emphasized that 6- to 7-wk BFU-E are endowed with the potential for in vitro synthesis of not only epsilon- and gamma-chains but also some beta-globin. In general, we observed an inverse correlation between the levels of epsilon- and beta-chain synthesis. These results, together with previous studies on fetal, perinatal, and adult BFU-E, are compatible with models suggesting that in ontogeny the chromatin configuration is gradually modified at the level of the non-alpha gene cluster, thus leading to a 5'----3' activation of globin genes in a balanced fashion.

Embryo, Mammalian↗
PubMed1984

Delta beta-thalassaemia in southern Italy: evidence for a single mutational event.

Haematological and molecular studies on 32 heterozygotes for G gamma A gamma delta beta(0)-thalassaemia from 15 unrelated families from southern Italy are reported. The haematological features of G gamma A gamma delta beta(0)-thalassaemia carriers are compared with those of beta-thalassaemia and Hb Lepore heterozygotes. Striking similarity exists between the phenotypic expression of beta-thalassaemia and Lepore mutations. Globin gene mapping studies indicated that the molecular lesion underlying delta beta-thalassaemia is a large deletion starting from the large intervening sequence of the delta gene and extending downstream from the beta gene. The possibility that delta beta-thalassaemia haplotypes in southern Italy originated from a single mutational event is discussed.

Chromosome Deletion↗
PubMed1984

Association of heterocellular HPFH, beta(+)-thalassaemia, and delta beta(0)-thalassaemia: haematological and molecular aspects.

An Italian family in which heterocellular hereditary persistence of fetal haemoglobin (HPFH) interacts with both beta(+)- and delta beta-thalassaemia is described. The index case was an 8 year old girl who was presumed to inherit both heterocellular HPFH and beta (+)-thalassaemia from her mother and delta beta-thalassaemia from her father. She was healthy and never needed blood transfusions. The possible contribution of heterocellular HPFH to the less severe expression of the compound delta beta/beta(+)-thalassaemia heterozygosity is discussed. By DNA analysis the specific delta beta-thalassaemia defect on the gamma delta beta globin gene region has been established. In addition, a previously unreported association of a polymorphic restriction site haplotype with a beta (+)-thalassaemia mutation has been observed.

Adult↗
PubMed1984

Methisoprinol restoration of leukocyte chemotaxis inhibition by blocking factors in immunoproliferative diseases.

The ability of methisoprinol to antagonize the serum-inhibiting activity present in the sera of patients affected by immunoproliferative diseases (Hodgkin's disease and multiple myeloma) was investigated. Using a chemotaxis test, it was found that whereas donor leukocytes preincubated in patient sera exhibited impaired chemotaxis, the presence of methisoprinol (500 micrograms/ml) during the preincubation caused a significant recovery of this leukocyte function. Since the results exclude the assumption of a non-specific stimulation of cell motility, two hypotheses appeared possible for the action of methisoprinol: either an antagonistic activity against the blocking factor at the receptor or the metabolic level, or a direct inactivation of this factor. The clinical implications, with regard to the prophylaxis of infections and a better response to chemotherapy, are discussed.

Adult↗