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Biomedical subjects

A Pessina

Publications and source records attributed to A Pessina.

At least 55 records · Page 3Linked to original sources
PubMed1986

Colony-stimulating factor produced by murine adrenocortical tumor cells.

Conditioned medium obtained from the adrenocortical LAF1 mouse tumor (Y-1) cell cultures was able to stimulate the proliferation and the differentiation of granulocyte-macrophage precursors in the normal murine bone marrow. Colony-stimulating factor (CSF) was spontaneously produced by Y-1 cells also in serum-free cultures. By two cycles of gel chromatography on Sephadex G-150 of concentrated conditioned medium two peaks of colony-stimulating activity were isolated that corresponded to apparent molecular radii of 100,000 and 29,000, respectively. At this step of purification, the two factors gave a similar dose-response curve, showed a remarkable resistance to the heat treatment and pH changes, and were not extracted by ether. Because Y-1 cells resulted in infection by retrovirus, they provide a useful model to investigate the relations between viral coded information and CSF production.

Adrenal Cortex Neoplasms↗
PubMed1985

Production of colony stimulating factor by EL-4 lymphoma cells stimulated with phytohemoagglutinin.

Murine EL-4 lymphoma cells when stimulated with optimal doses of phytohemoagglutinin (PHA) release colony stimulating factor (CSF) in the conditioned medium. CSF production depends on PHA and stops when the lectin is withdrawn. The production is dependent on protein synthesis and is not related with DNA replication. The CSF produced by El-4 cells stimulates murine bone marrow cells to differentiate in vitro into mature granulocytes. Unstimulated EL-4 cells do not produce CSF while its conditioned medium is able to inhibit EL-4 proliferation in vitro. Gel filtration chromatography of conditioned medium from PHA-stimulated EL4 cells yields a peak of activity corresponding to an apparent molecular weight of 20,000-25,000 daltons.

Animals↗
PubMed1985

Analysis of spontaneous deletion mutants of satellite bacteriophage P4.

Spontaneous deletion mutants of satellite bacteriophage P4 have been isolated and characterized. All of the deletions analyzed that were between 850 and 1,700 base pairs long are within the region nonessential for P4 lytic development; some of them cover the cII or the gop locus.

Bacteriophages↗
PubMed1985

Isolation and partial characterization of temperature bacteriophages from enteropathogenic strains of Escherichia coli 0111:K58.

We report studies on ten strains of Escherichia coli 0111:K58 isolated from children with acute diarrhea. Our results show that these E. coli strains do not produce the pathogenic factors of enterotoxic E. coli (ETEC) and are lysogenic for phages belonging to two groups that differ for host range, kinetics of thermal inactivation, antigenicity and morphology. These data support the hypothesis that these phages may in vivo contribute to reduction of the number of common E. coli strains by lytic infection favouring the development of the enteropathogenic strain of E. coli.

Child, Preschool↗
PubMed1984

Modulation of EL-4 mouse lymphoma cell proliferation by macrophages and tumor related factors.

It is well known that macrophages play an important role in the control of tumor growth. This control may be the result of a direct action of macrophages or mediated by several biologically active products or factors elaborated by these and other cell populations. Our studies on the proliferation of a murine T-cell lymphoma (EL-4) showed that the treatment of the ascitic fluid (from the peritoneum of EL-4 bearing mice) with carbonyl iron resulted in a depletion of phagocytes concomitant with a significant increase of [3H] thymidine uptake by EL-4 cells. Further, the growth of EL-4 cells cultured in semisolid agar was significantly inhibited by an underlayer of large quantities of macrophages both from normal and EL-4 bearing mice as well as when cultured in the presence of PGE2. The underlayer of tumor macrophages P388 D1 resulted in an increase of the EL-4 cell growth. Also, conditioned media obtained from in vitro liquid cultures of EL-4 cells and L 1210 cells (B-lymphoma) produced a remarkable inhibition of the in vitro cloning capacity and [3H] thymidine uptake by EL-4 cells. These data support the hypothesis that different factors from normal and hemopoietic tumor cells may control the tumor growth and point out that self-produced factors may modulate the proliferation of tumor cells.

Animals↗
PubMed1983

Inhibition of granulocytic-macrophagic precursor cells (CFU-C) by heat-labile enterotoxin (LT) produced by Escherichia coli.

Enterotoxigenic strains of Escherichia coli cause diarrhea by production of heat-labile enterotoxin (LT) which acts through stimulation of membrane-bound adenylate-cyclase in epithelial cells. We studied in vitro production of LT by growing E. coli H 10407 in different synthetic media in comparison with Penassay broth. Non-toxigenic E. coli K12 was used as control. We obtained positive response in Y-1 cell assay for LT activity with all filtrates from E. coli H 10407 cultures. These filtrates inhibit 3H-thymidine uptake by Ehrlich Ascites Carcinoma (EAC) cells and the proliferation of granulocytic-macrophagic precursors (CFU-C) in murine bone marrow. Filtrates did not stimulate CFU-C in absence of CSF. Heat-treated (121 degrees C for 30 minutes) and dialyzed (molecular cut 15,000 daltons) filtrates lost their cytotoxicity against Y-1 cells maintaining the inhibitory activity on CFU-C proliferation. This phenomenon may be regarded as the result of a competitive mechanism between LT and CSF (Colony Stimulating Factor) on the receptor system of committed stem cells.

Animals↗
PubMed1982

Factors produced by macrophages and tumor cells: influence on the granulocytic precursor cells (CFU-C) in normal and tumor-bearing mice.

Some tumors are known to produce colony-stimulating factors (CSF). In mice bearing s.c. Ehrlich tumor (ET) we observed that tumor growth is responsible for hemopoietic perturbations in which the increase of granulocytic-macrophagic precursors (CFU-C) in bone marrow and in the spleen represents a remarkable aspect. CFU-C in bone marrow from ET-bearing mice are more sensitive than CFU-C from normal mice to CSF from L-cells (LC-CM), mouse embryo fibroblasts (MEF-CM) and from the same tumor (ET-CM). Macrophages from normal and from ET-bearing mice exert the same effect on the proliferation of normal bone marrow CFU-C. Bone marrow CFU-C from ET-bearing mice show an increased sensitivity to the inhibitory factors produced by macrophages from ET-bearing mice.

Animals↗
PubMed1982

CFU-s and CFU-c proliferation after treatment of normal bone marrow cells with Ehrlich ascitic fluid.

The possible role of some soluble factor produced by tumor cells or by tumor-host interaction on homeostatic mechanism of normal bone marrow was investigated. Our data show that the in vitro pretreatment of normal bone marrow cells with Ehrlich acellular ascitic fluid (EAF) produces a severe reduction of the number of colonies either in CFU-s (colony-forming unit-spleen assay for pluripotent stem cell compartment) or in CFU-c (colony-forming unit-culture test for granulocytic committed compartment). The differentiation of CFU-s and CFU-c was also affected in respect to the controls. In fact, when normal bone marrow cells were pretreated with EAF the proportion of erythroid colonies deriving from CFU-s changed in favor of the undifferentiated one, while the proportion of pure granulocytic colonies was increased in the CFU-c assay.

Animals↗
PubMed1981

Effect of tumor-related factors on the in vivo and in vitro colony-forming ability of normal mouse marrow cells.

The effect of normal mouse marrow preincubation with Ehrlich tumor fluid (EAF) and Ehrlich tumor cell-conditioned medium (ET-CM) was investigated both on the in vivo assay for pluripotential stem cells (CFU-S) and on the in vitro assay for granulocytic-macrophagic progenitors (CFU-C). A significant reduction of the number of CFU-S was found when bone marrow cells were incubated with EAF. The morphological analysis showed a relative increase in the granulocytic type colonies besides an absolute increase in undifferentiated ones and an absolute decrease in erythroid colonies. The in vitro data show a decrease in CFU-C production, by stimulation with standard Colony Stimulating Factor (CSF), when the marrow cells are preincubated with EAF and ET-CM. When standard CAF (obtained from L-cells) is used at the higher concentrations, the CFU-C in the ET-CM treated marrow increases to the control values. EAF and ET-CM incubation also affects the CFU-C differentiation by increasing the number of pure granulocytic clones. The experimental data were discussed in order to explain an hypothesis about the activity of tumor-related factors.

Animals↗