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S Mardente

Publications and source records attributed to S Mardente.

13 recordsLinked to original sources
PubMed2000

C3 synthesis and CRs expression during differentiation of a murine stem cell line.

C3 production, release and CRs expression during the neutrophilic differentiation of a murine non tumorigenic cell line is investigated. The murine non tumorigenic cell line 32DCl3(G) which undergoes terminal differentiation into polymorphonuclear granulocytes when cultured in presence of G-CSF was selected as a suitable in vitro model for this study. The results show that as the cells progress into the differentiation program, levels of C3 mRNA increase, accompanied by increased C3 production. As differentiation progresses the cells gradually express CRs on their surface; these are undetectable on the surface of undifferentiated cells. As a consequence of CRs appearance, cells become able to bind C3 through receptorial binding. Differences were found in the modality of C3 secretion: differentiated cells tend to store C3 in their intracellular compartments rather than secrete it continuously into the medium and they respond to membrane stimulation with increased secretion of C3. Treatment of 32DCl3(G) with TNF-alpha increased C3 production in a time- and dose-dependent fashion. Cell response to this stimulus progressively increases during the differentiation process suggesting that they acquire functionality in the signal transduction mechanisms.

Animals↗
PubMed1999

C3 molecules internalize and enhance the growth of Lewis lung carcinoma cells.

C3 molecules from normal murine serum are mainly bound to Lewis lung carcinoma cells (3LL) that do not express CRs, mainly through covalent binding as determined by the appearance of bands stained with anti-C3 and larger than 190 kD in immunoblots of proteins in whole cell extracts. Methylamine-treated, or zymosan-treated normal mouse serum, heat inactivated, or EDTA-treated murine serum resulted in low C3 deposition on 3LL cells, as indicated by fluorescence tests and immunoblotting. Cytofluorimetric studies showed that C3 molecules bound to 3LL cells were internalized in a time- and temperature-dependent process. This was confirmed by electronmicroscopic studies. The conditions allowing C3 fixation to acceptor sites and subsequent internalization increased cell proliferation. This was also true, when serum from mice genetically deficient in C5 was used which stresses the role of C3 in contrast to effects of membrane attack complex formation.

Animals↗
PubMed1992

Phenotypic and functional modifications of thymocytes during tumor growth.

Thymocytes (T) from mice bearing the syngeneic tumor 3LL inhibit the immune response to SRBC by syngeneic splenocytes derived from control mice and cultured in Mishell and Dutton's antibody forming systems. T from control mice are devoid of this capacity but acquire it after in vitro incubation with tumor cells. It has been shown that metabolites of arachidonic acid (PGE-2, LTB-4 and LTC-4) synthesized in excess by tumor cells act as mediators for the acquisition of the above capacity by thymic cells in vitro. Surface phenotypical analysis by flow-cytometry demonstrated that in the thymus of tumor bearing mice the proportion of both single positive thymocytes (L3T4+/LY2- and L3T4-/LY2+) and of double negative thymocytes (L3T4-/LY2-) increased with a parallel decrease in the proportion of double positive cells (L3T4+/LY2+). In the mean time the total number of thymocytes markedly decreased. An attempt was done to mimic in vitro what happens in vivo. For this purpose T from control mice were incubated with conditioned culture medium in which 3LL cells had grown or with arachidonic acid metabolites. After one or the other of these treatments T from control mice did not modify their phenotypic antigenic pattern but acquired the capacity to negatively interfere with the in vitro immune response of normal spleen cells to SRBC. Since serum from tumor bearing mice contains large amounts of PGE-2, LTB-4 and LTC-4 we tested its effects on normal syngeneic T. Serum from tumor bearing mice, but not serum from normal mice, induces T from control syngeneic animals to acquire both immunosuppressive capacity and differentiation pattern clusters similar to those that characterize T derived from the thymus of tumor bearing mice. We demonstrated that metabolites of arachidonic acid are active as inducers of immunosuppressive capacity in T. On the other hand, a yet unknown factor present in serum of tumor bearing mice plays a role as inducer of differentiation of these cells.

Animals↗
PubMed1990

Interferon gamma increases in vitro and in vivo expression of C1 inhibitor.

C1 inhibitor (C1 INH) is the major protease inhibitor of the first components of the classic complement system and of the proteases of the Hageman factor pathways. Since C1 INH may modulate inflammatory reactions associated with complement and contact system activation, we sought to determine if the cytokine gamma interferon (IFN-gamma) could modulate C1 INH production. Initial studies investigated the effect of IFN-gamma on the molecular and protein expression of C1 INH in human erythroleukemia (HEL) cells. HEL cells constitutively expressed the 2.1 kb mRNA for C1 INH. IFN-gamma (50 to 1,000 U/mL), but not interferon alpha or beta, increased twofold the amount of C1 INH mRNA expressed within HEL cells. Similarly, this cytokine increased HEL cell C1 INH synthesis of a 105 Kd protein 10-fold, from 1.9 +/- 0.5 microgram C1 INH antigen per 10(8) cells (mean +/- SEM) to 19 +/- 8 micrograms/10(8) cells in 8 days. C1 INH produced by HEL cells after IFN-gamma stimulation had fully intact kallikrein neutralizing activity. Moreover, conditioned media of IFN-gamma-treated HEL cells accumulated more secreted C1 INH in 8 days (6.7 micrograms/mL/10(8) cells) than untreated cells (0.6 microgram/mL/10(8) cells). Additional studies were done on plasma specimens from 22 patients with metastatic colorectal carcinoma who received IFN-gamma daily for 4 days by intravenous infusion. Before treatment, the mean +/- SEM C1 INH levels in these patients was 438 +/- 16 micrograms/mL. At day 10 from the start of the infusion, the plasma C1 INH in these patients increased to 586 +/- 32 micrograms/mL (P less than .0001). The extent of rise of plasma C1 INH after IFN-gamma treatment was independent of dose from 0.01 to 40 U/m2. After 30 days, the mean plasma C1 INH levels decreased to 502 +/- 27 micrograms/mL. These combined studies indicate that IFN-gamma can increase C1 INH protein expression in vitro and in vivo.

Blotting, Northern↗
PubMed1989

Chemotactic response of rat macrophages is enhanced by two diastereoisomers of LTB4.

We demonstrated that rat peritoneal cells synthesize, and release into the culture medium, substances that elicit a chemotactic responsiveness of rat macrophages. These substances were identified by HPLC analysis as two diastereoisomers of LTB4, precisely delta-6-trans-LTB4 and delta-6-epi-trans-LTB4. Peritoneal cells release, also, other lipoxygenase metabolites such as LTD4 and LTB4, which were shown not to be active in eliciting chemotaxis of rat macrophages, in agreement with data of other authors. Quantitative assays for the measurement of PMNs or macrophage chemotaxis were carried out in Boyden chambers. Release of leukotrienes by rat peritoneal cells into the culture medium was strongly enhanced upon stimulation with calcium ionophore A23187, an agent known to increase cytoplasmic Ca2+ concentration, thus leading to the activation of Ca2+-dependent phospholipase and a consequent increase in the amount of endogenous free arachidonic acid available for biotransformation. The action of several inhibitors of arachidonate metabolism at concentrations more selective for the lipoxygenase than the cycloxygenase pathway, was also studied. alpha-Tocopherol and ASA were shown to be the most selective in inhibiting the synthesis of both the LTB4 diasteroisomers active as enhancers of rat macrophage chemotaxis.

Animals↗
PubMed1988

Lewis lung carcinoma cells enhance the synthesis of C3 and are opsonized by C3 secreted from murine macrophages.

We investigated the effect of Lewis Lung carcinoma cells on the production of C3 by murine macrophages and examined the capacity of secreted C3 to opsonize Lewis Lung carcinoma cells. C3 released in culture from macrophages obtained from tumor-bearing C57Bl/6 mice as well as from normal macrophages exposed to Lewis Lung carcinoma cells in vitro was measured by hemolytic assays and by Western blot. We found that contact with tumor cells in vivo as well as in vitro enhanced the amount of C3 secreted by murine macrophages by a factor of 2-3. The inflammatory agent carrageenan caused only a small increase in the amount of secreted C3. On Western blots of concentrated macrophage supernatants, there was partial cleavage of secreted C3 which was, however, not more pronounced in the case of C3 from tumor-stimulated macrophages than from normal macrophages. Supernatants from normal as well as tumor-stimulated macrophages were capable of opsonizing Lewis Lung carcinoma cells as shown by their capacity to bind human erythrocyte in an immune adherence reaction. Pretreatment of the tumor cells with a protease inhibitor, PMSF, inhibited the capacity of the tumor cells to bind C3, suggesting that a tumor cell-associated protease might be involved in the binding of C3 to the tumor cell surface.

Animals↗
PubMed1981

GLC-ECD determination of 1-(2-hydroxyethyl)-3-hydroxy-7-chloro-1,3-dihydro-5-(O-fluorophenyl)-2H-1,4-benzodiazepin-2-one (SAS 643) in plasma and urine and identification of its main biotransformation products.

A method using gas-liquid chromatography-electron-capture detection method is described for rapid, accurate determination of SAS 643 in plasma and urine. The drug is extracted from biological fluid with benzene and converted to the O, O'-bistrimethylsilyl derivative with bis(trimethylsilyl) trifluoroacetamide. The glucuronide form of the drug is extracted after hydrolysis with beta-glucuronidase. Nimetazepam is used as internal standard. Moreover, some metabolites such as glucuronide and the N-1-dealkylated and N-1-yl-acetic products are identified. All compounds were confirmed by thin-layer chromatography, mass spectroscopy, and gas-liquid chromatography-mass spectroscopy by comparison with reference products.

Anti-Anxiety Agents↗
PubMed1975

GLC determination of hexadiphane in pharmaceutical preparations.

A specific, rapid, and sensitive GLC method for purity control of hexadiphane and its determination in pharmaceutical perparations is described. The method utilizes an extraction of the free base, followed by GLC on a 0.5% OV-17 column at isothermal temperature for 6 min and then the temperature was programmed. Results from this method and from a titrimetric method were compared, and no significant differences were found.

Azepines↗