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Biomedical subjects

C Riccardi

Publications and source records attributed to C Riccardi.

160 records · Page 9Linked to original sources
PubMedDate not supplied

Focused ion beam characterization of plasma-assisted deposition on polymer films at the nanoscale.

In this paper, a novel technique is presented for the characterization at the nanoscale of plasma-assisted deposit on polyethylene-terephthalate (PET) polymer films. In previous studies, some microcharacterization and morphology analyses of plasma-assisted deposition were performed by atomic force microscopy (AFM). In the work presented here, we analysed the thickness and homogeneity of plasma-assisted deposits by focused ion beam (FIB). This technique with 5-7 nm resolution requires no sample preparation and relies on a sequence of operations on a relatively fast time scale, so that it is easy to make thorough investigations of the sample. We performed electron and ion imaging of the surface of the material, and a subsequent ionic cutting allowed the study of the morphology of the same sample. We developed a novel approach to the edge detection techniques (EDT) in images for a fast evaluation and monitoring of the deposited layer.

Journal Article↗
PubMedDate not supplied

Glucocorticoid hormones in the regulation of cell death.

The immune T-cell compartment maintains the capability to respond to a wide variety of antigens (Ag). This whole process is regulated by lymphocyte apoptosis (programmed cell death, PCD) and involves the coordinated expression of a great number of genes including those coding for cytokines and their receptors, such as for example IL-2/IL-2R and the Fas/FasL systems and those coding for transcription factors, including the NF-kB complex, involved in T-cell activation and apoptosis in that they simultaneously activate cell suicide and an anti-death programme. This binary effect, PCD activation and inhibition, is due on one hand to GCH-induced activation of the caspases cascade and on the other to the induction of expression of a new gene that we have named GILZ. In fact, GILZ over-expression in transfected cells inhibits the sequential increase of NF-kB/DNA-binding activity, IL-2 production and IL-2R expression, and transcription of the Fas/FasL complex that follows TCR triggering and plays an important role in the control of T-lymphocyte apoptosis. These results indicate a new mechanism responsible for the GCH-mediated inhibition of T-cell death and activation that could contribute to anti-inflammatory and immunosuppressive efficacy.

Animals↗
PubMedDate not supplied

Model for the study of the impact of atmospheric heavy metals on soil microbial biomass.

In the Castelporziano (Rome) protected area the inputs of atmospheric heavy metals on the soil-plant system were evaluated by the analysis of stem-flowing water from Quercus ilex L. The heavy metals detected in the soil under the canopies exhibited higher concentrations near to the tree trunks, highlighting the tree's capacity to concentrate such polluting substances. Microbial biomass, its specific respiration and the biomass calculated as a percentage of total soil organic matter, were utilised as indicators of the state of the soil and consequently also its quality with respect to heavy metal contamination.

Air Pollutants↗
PubMedDate not supplied

Long-term cultures of mouse bone marrow cells: a model for studying the generation of natural killer cells.

We investigated the generation of natural killer (NK) cells, using a long-term bone marrow culture (LTBMC) system. Mouse bone marrow cells were cultured for 2 weeks in complete medium without growth factors to obtain an enriched population of NK precursor cells. When these cells were recultured in the presence of interleukin-2 (IL-2) and conditioned medium (CM) from LTBMC, lytic NK cells were generated within 4 days. Replacing CM with fresh medium, before adding IL-2, decreased NK cell generation markedly, suggesting that endogenous factors present in CM were necessary for IL-2 induction of NK cells. NK cell precursors were also cultured with a combination of IL-2 and interferon-gamma (IFN-gamma) or IL-2 and tumor necrosis factor-alpha (TNF-alpha), but no CM. Results show that IFN-gamma and TNF-alpha were able to substitute CM. The addition of anti-IFN-gamma or anti-TNF-alpha antibodies to LTBMC cells, cultured in the presence of IL-2 and CM, inhibited cytotoxicity induction in a dose-dependent manner. The data indicate that IFN-gamma and TNF-alpha production may be required for IL-2 induction of NK activity, and are consistent with the hypothesis that NK generation involves collaboration between IL-2 and other bone marrow microenvironmental growth factors.

Animals↗
PubMedDate not supplied

Effect of recombinant murine tumor necrosis factor on the generation of natural killer cells in bone marrow cultures.

We investigated the possible role of tumor necrosis factor-alpha (TNF-alpha) in the interleukin-2 (IL-2)-dependent generation of natural killer (NK) cells from bone marrow precursors. TNF-alpha synergistically augmented both cytotoxic activity against NK-sensitive targets and cell number at the end of the 7-day incubation period. After this time, NK activity was not induced by TNF-alpha in the absence of IL-2. The cytotoxic cells generated by IL-2 + TNF-alpha had the phenotype of mature NK cells, including expression of NK-1.1, asialo-GM1, Ly-5, LFA-1 and Thy-1. TNF-alpha was also able to up-regulate the mRNA expression for the IL-2 receptor alpha-chain (P55) as well as the mRNA expression of c-myc protooncogene. Blocking studies with monoclonal antibodies against the alpha-chain P55 of the IL-2 receptor confirmed the functional role ascribed to IL-2 in the in vitro generation of NK cells from bone marrow cultures. Additional proliferation studies demonstrated that the up-regulation of c-myc protooncogene was associated with an increased uptake of thymidine. These data indicate that the TNF-alpha-induced increase of IL-2-dependent NK cell generation from bone marrow precursors was associated with an augmented proliferation and an up-regulation of mRNA expression for IL-2 receptor and c-myc protooncogene.

Animals↗
PubMedDate not supplied

In vitro generation of natural killer cells from SJL/J bone marrow precursors.

The development of natural killer (NK) cells from undifferentiated bone marrow (BM) precursors of low-NK-reactive SJL/J mice was studied. Results indicate that BM cells of untreated mice are not able to generate NK effector cells in cultures supplemented with recombinant interleukin-2 (IL-2). On the other hand in the presence of IL-2, NK cells are generated in cultures of BM from mice pretreated with 5-fluorouracil (5-FU, 150 mg/kg iv 4 days before harvesting), a treatment which has been shown to eliminate more differentiated but spare less differentiated BM precursors. The 5-FU resistant BM progenitor is asialoGM1-, Thy.1+, Lyt.1- and Lyt.2-. The cells generated by culturing with IL-2 are asialoGM1+, Thy.1+, Lyt.5+, Lyt.1-, Lyt.2- and lyse only NK-susceptible targets. Generation of NK cells is blocked by addition of anti-IL-2 receptor (IL-2/r) antibodies. These studies demonstrate that it is possible to generate NK effectors from SJL/J BM cells by in vitro culturing with IL-2.

Animals↗
PubMedDate not supplied

Partially restorative role of T cells for low interleukin 2 dependent growth of NK cell progenitors from nude mice.

The frequency of cells in the spleens of nude mice which could be grown in conditioned medium containing interleukin 2 and of those which developed natural killer (NK)-like activity was evaluated. Although BALB/c nu/nu spleen cells have higher spontaneous NK activity than euthymic mice, they showed a substantially lower frequency of proliferating and cytotoxic cells as compared to BALB/c nu/+ littermates. This defect in cells of nu/nu mice was reversed in part by culturing nu/nu responder cells in the presence of irradiated (3,000 R) splenic or thymic feeder cells that included T cells. In contrast to the dissociation of NK activity and progenitor frequencies in nude mice, the results of parallel studies with spleen cells from euthymic mice indicated that the limiting dilution assay correlated well with previously described features of NK activity. High-NK-reactive CBA/J mice were found to have a considerably higher frequency of interleukin 2 dependent NK cell progenitors than low-NK-reactive strains of mice when assessed against NK-susceptible YAC-1 targets. The frequency of progenitors of cells cytotoxic against YAC-1 was higher in spleens of high-NK-reactive mice than that of cells reactive against the NK-insensitive target P-815. Furthermore, the phenotype of the progenitor cells and of the cultured effector cells was consistent with that of NK cells rather than cytotoxic T cells in that the cells expressed asialo GM1, some Thy-1, but no detectable Lyt-1 or Lyt-2 antigens. Thus, the present observations suggest that the subpopulation of NK cell progenitors in nude mice which can grow and develop cytotoxic reactivity in vitro in the presence of interleukin 2 is small, that it can be increased appreciably in the presence of T cells, but that this does not represent the major pathway for development of NK cells in athymic individuals.

Animals↗
PubMedDate not supplied

Protein tyrosine kinase inhibition and cell proliferation: is the [3H]-thymidine uptake assay representative of the T-lymphocyte proliferation rate?

T-cell growth is controlled to a large degree by extracellular signals that bind to specific receptors on the surface of cells. A number of these receptors have intrinsic protein tyrosine kinase (PTK) activity. Their action on second messenger generation, and thus on cell proliferation, has been indirectly demonstrated by the decrease in [3H]-thymidine (TdR) uptake that follows co-stimulation of T-cells with mitogens and PTK inhibitors such as genistein (GEN). In this paper we report that the [3H]-TdR uptake assay is not a valid and reliable tool for investigating the proliferative activity of certain T-cell lines. In fact, a concomitant assessment of both [3H]-TdR uptake and cell cycle progression demonstrated that GEN is able to block G2/M progression of Jurkat T-lymphocytes even at doses (5 micrograms/ml) that do not influence [3H]-TdR uptake. Pretreatment with sodium o-vanadate (100 nM) could not reverse the GEN-related cell cycle perturbation, but was able to restore optimal [3H]-TdR uptake. Finally, GEN treatment was able to induce concentration-dependent apoptotic cell death of Jurkat T-cells. The control of cell activation, proliferation and programmed cell death is undoubtedly influenced by receptor-associated PTKs. The final effect on cell survival is almost entirely dependent on the activation state of the cell. The [3H]-TdR uptake assay seems to be inadequate for a correct interpretation of the expected results.

Cell Cycle↗
PubMedDate not supplied

Slow and unrecognized progression of schwannoma of the sciatic nerve.

Schwannoma of the sciatic nerve is a rare occurrence, responsible for aspecific symptomatology, frequently confused with nerve root deficit caused by discopathy. Diagnosis is usually made several years after onset, also because electromyographic examination is normal. Once tumor swelling has been identified, several instrumental tests and intraoperative macroscopic examination provide sufficient elements for diagnosis: histological examination shows typical aspects.

Humans↗