Search PubMed⌕ Search

Biomedical subjects

L Pegoraro

Publications and source records attributed to L Pegoraro.

At least 91 records · Page 5Linked to original sources
PubMed1982

[Phagocytic activity and cytochemical characterization of acute human myeloblastic leukemia cells].

The ability of leukemic cells to phagocytize in vitro inert latex particles was tested in a group of non-lymphoblastic acute leukemia causes classified according to the FAB criteria. Promyelocytic, myelomonocytic, and myeloblastic leukemias were found to possess the highest percentage of cells with phagocytic activity. The cytochemical characterization of the cells revealed that the majority of phagocytic elements were negative for alpha-naphtyl acetate staining and positive for the peroxidase reaction. These unexpected findings could be explained by the impaired differentiation process of leukemic cells.

Humans↗
PubMed1982

[Expression of HLA-DR structure and a membrane-specific antigen by a granulocytopoietic line of acute leukemic blast cells].

Blast cells from peripheral blood of 32 patients with acute leukemia were tested for their ability to react with a monoclonal antibody (D1.B6) specific for HLA-DR surface antigen. In order to evaluate the degree of leukemic cell differentiation a monoclonal antibody (R1.B19) specific for the granulocytopoietic lineage was also employed. The results demonstrated that a considerable proportion of blast cell populations expressed the HLA-DR antigen, while only a small fraction of cells expressed the myeloid antigen.

Antibodies, Monoclonal↗
PubMed1982

Release of platelet-activating factor from HL-60 human leukemic cells following macrophage-like differentiation.

Platelet-activating factors (PAF), a phospholipid mediator of anaphylaxis, is also known to be released in vitro from both phagocytic polymorphonuclear neutrophils (PMN) and monocytes in response to a variety of stimuli. The fact that human myeloid cells of the HL-60 line can be made to differentiate in vitro into macrophage-like cells by 12-O-tetradodecanoylphorbol-13-acetate (TPA) prompted us to investigate the generation and release of PAF during this transformation. Both passive release of PAF at pH 9.5, and active release, following phagocytosis of C3b- and C3d-opsonized yeast spores, and stimulation with C5a anaphylatoxin from untreated and TPA-treated HL-60 cells, PMN, and plastic-adherent normal human monocytes were studied. It was found that after 3 days of TPA treatment, HL-60 cells released PAF following phagocytosis of C3b- and C3d-opsonized yeast spores. Inhibition of PAF release by a selective inhibitor of phospholipase A2 and labeling of PAF with sodium 14C-acetate indicated that PAF generation is a two-step process: (1) release of PAF precursor from cell membranes and (2) its acetylation. A model for the in vivo study of mechanisms and metabolic events involved in PAF generation and release could perhaps be built on these findings.U

Cell Line↗
PubMed1981

DNA synthesis and cell generation pattern of chronic lymphatic leukaemia lymphocytes stimulated by phytohaemagglutinin.

A detailed analysis of the cell recruitment and of the cell generation pattern of normal lymphocytes and chronic lymphatic leukaemia (CLL) lymphocytes, simulated by phytohaemagglutinin (PHA), was performed by the bromodeoxyuridiine (BUdR) Hoechst technique. It was found that in normal cultures the majority of cells divide two or three times, producing an early peak of DNA synthesis, while only a few cells grow exponentially and pass through many rounds of replication. On the contrary, the majority of CLL responsive cells grow exponentially, producing a delayed peak of DNA synthesis, while cells which divide only two or three times are scarce or absent. No difference in the minimal cell cycle length of the normal and the CLL exponentially growing population was found. In addition, a cell population recruited into cycle for the first time 5-6 days following PHA stimulation was observed in normal cultures but not in CLL cultures.

Cell Cycle↗
PubMed1981

Effects of aspirin treatment upon fibrinolytic activity of peripheral blood granulocytes.

The effects of in vivo acetylsalicylic acid (ASA) treatment on the fibrinolytic activity of peripheral blood granulocytes have been studied in a group of healthy volunteers. Following a 4-day treatment with aspirin at a dose of 1 g/day, both the plasminogen-dependent and the nonspecific fibrinolytic activity were significantly decreased. On the contrary, no significant change in the granulocyte fibrinolytic activity was found after treatment with 250 mg ASA/day. It is suggested that the cellular release mechanism of such lytic enzymes rather than their synthesis could have been affected by the drug.

Adolescent↗
PubMed1980

[Changes of fibrinolytic activity of human HL60 acute leukemia cells responses to chemically induced differentiation].

The fibrinolytic activity of human acute leukemia HL 60 and K 562 cells was studied by the (I25)I-fibrin plate method. The treatment of this cell lines with chemical inducers of differentiation such as Dimethyl sulfoxide (DMSO), 12-0-tetradodecanoilphorbol 13-acetate (TPA), and retinoic acid was found in some instance to affect such fibrinolytic activity. Increased activity was found during the myeloid differentiation induced by retinoic acid of HL 60, while the DMSO, another inducer of myeloid differentiation, and TPA, an inducer of macrophagic differentiation, both produced a decreased of the lytic activity. In the treatment with retinoic acid of th K 562 cells, which do not differentiate by such compound, we failed to show an increase of the fibrinolytic activity. Our data suggest that changes of the fibrinolytic activity of HL 60 are related to the process of differentiation.

Cell Differentiation↗
PubMed1980

[Insulin receptors in the HL60 human promyelocytic leukemic cells line].

The insulin binding characteristics of human promyelocitic HL60 cell line was studied by the use pf I(125) insulin. The binding activity was found to increase linearily both with the number of cells and with the incubation time. The competition curve with increasing concentration of unlabeled insulin demonstrated of specific receptors. The number of receptors was estimated to be 6.36 . 10(6) per cell.

Cell Line↗
PubMed1980

[Decrease of insulin binding to human acute leukemic cells during chemically induced differentiation].

The specific insulin binding activity of human promyelocitic HL 60 cell line during the myeloid and macrophagic differentiation induced by chemical compounds was investigated. Dimethyl sulfoxide (DMSO) and retinoic acid myeloid induced differentiation in HHL 60 cells was accompanied by a marked decrease of insulin receptors. In K 562 cell line, where DMS O has no effect on differentiation, the number of insulin receptors was only slightly affected. 12-0-tetradodecanoil phorbol 13-acetate (TPA) induced macrophagic differentiation of HL 60 cell line was also accompanied by a decrease of insulin binding activity. Our results support the hypothesis that during the process of terminal differentiation a decrease of insulin receptors occurs.

Cell Differentiation↗
PubMed1980

[Fibrinolytic activity of human peripheral blood granulocytes].

The fibrinolytic activity of human peripheral blood leukocytes was studied by plating the cells on 125I-fibrin coated dishes. The separation of the three major leukocyte types allowed to demonstrate that most of the activity was produced by granulocytes. The rate of fibrinolysin was found to be linear with incubation time and cell number in the range of 1-4 X 10(5) cells/ml. Since little activity was found in absence of exogenous plasminogen, it was concluded that the cell fibrinolytic activity depended mostly upon the release of plasminogen activator. Plasmatic and granulocytic activators obtained from the same amount of blood were found to be of similar level suggesting a possible clinical implication of the cellular activity in the thrombolytic system.

Blood Cells↗
PubMed1980

Differentiation of human leukemias in response to 12-0-tetradecanoylphorbol-13-acetate in vitro.

Leukemic cells from patients with acute myeloid leukemia underwent morphological, functional, and histochemical changes within 24-48 hr after treatment with 1.6 x 10-18 M 12-0-tetradecanoylphorbol-13-acetate (TPA). The changes included adhesion to the plastic substrate, a 4-6-fold increase in the number of phagocytic cells, and an increase in the number of alpha-naphthyl-acetate esterase (alpha-NAE) positive cells. In contrast, TPA treatment of cells from patients with acute lymphoblastic leukemia caused some aggregation of cells in suspension, but no changes in adhesion, phagocytosis, or alpha-NAE. Of the four cases of undifferentiated or unclassified leukemias studied, two failed to respond to TPA, one responded with a myeloid (adhesion) pattern, and one with a lymphoid (aggregation) pattern. These data suggest that leukemic myeloblasts retain the ability to express a variety of differentiated functions, and in some cases, it may be possible to use TPA as a tool to test the differentiative potential of undifferentiated human leukemias.

Cell Adhesion↗
PubMed1976

Kinetics of phytohemagglutinin stimulated lymphocytes in chronic lymphocytic leukemia.

The DNA synthesis pattern and several kinetic parameters of in vitro PHA stimulated normal and CLL lymphocytes were determined. The DNA synthesis peak of CLL lymphocytes occurred 2-3 days later than that of normal lymphocytes. The generation time, estimated by the labeled mitoses method, was found to be 28 hr and 20 hr for CLL and normal lymphocytes respectively. This difference was mainly due to longer S and G1 periods. It was also shown that both CLL and normal lymphocytes divide several times. These data were confirmed by the chromatid labeling pattern and by the halving of the grains and the double labeling techniques. By combining continuous and pulse labeling the growth fraction of CLL lymphocytes was found to be progressively increasing, because of the recruitment of new cells in cycle, from the third day of culture. Therefore the delayed peak of DNA synthesis of CLL lymphocytes was caused by a longer cell cycle and by a longer pre-replicative phase.

Cell Division↗