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A Cataldi

Publications and source records attributed to A Cataldi.

At least 109 records · Page 6Linked to original sources
PubMed1993

Interferon rapidly induces modifications of chromatin sensitivity to DNase I in Daudi lymphoma cells.

The DNase I sensitivity of total chromatin has been analyzed in nuclei isolated from control and interferon-treated Daudi cells. The electrophoretic analysis of DNA has evidenced a different pattern of DNA fragment size produced by DNase I in nuclei isolated from control cells compared to interferon-treated samples. This feature is supported by a different recovery of acid soluble chromatin and is accompanied by modifications of in vitro RNA synthesis along with initiation and elongation of RNA chains. No changes have been evidenced in nuclei isolated from Daudi-resistant cells under the same experimental conditions. These data might be interpreted as a transient modulation, induced by interferon, of chromatin structure in terms of chromatin condensation which, in turn, activates the RNA synthesis after the transduction into the nucleus of the interferon-generated signals.

Burkitt Lymphoma↗
PubMed1993

Differential kinetics of propidium iodide uptake in apoptotic and necrotic thymocytes.

Apoptosis and necrosis represent two different mechanisms by which cells die. The dynamics of cellular lesions in these two processes differ. In particular we demonstrate that plasma membrane damage, occurring as a primary event during necrosis represents, on the contrary, a delayed but massive phenomenon during apoptosis. In consequence there are different kinetics of propidium iodide incorporation by necrotic and apoptotic thymocytes. This represents the basis for the flow cytometric identification of different cellular subsets. Analysis of these subsets after sorting showed that clearly apoptotic cells, which are not able to exclude propidium iodide for long incubation periods, do not show any morphologically detectable membrane damage. The kinetics of propidium iodide incorporation in vivo in isolated rat thymocytes can therefore be used in flow cytometric analysis. This technique can be used instead of DNA staining of ethanol-treated cells or nick translation to recognize apoptotic cells, and distinguish apoptosis from necrosis, without killing the cell.

Animals↗
PubMed1993

Calcitonin and beta-endorphin secretion.

Calcitonin is a peptide hormone secreted by the C-cells of the thyroid gland. This hormone mainly acts in preventing bone resorption. Furthermore, calcitonin is involved in other biological actions, and in particular it is able to relieve pain independently of its peripheral effects on bone. Here, we examine the possible mechanisms of calcitonin-induced analgesia, with particular regard to the opioid system involvement. Several studies in animals and in humans demonstrate that calcitonin increases plasma beta-endorphin levels, acting at the hypothalamic and/or at the pituitary level, either directly or indirectly, through monoaminergic neurotransmitters. However, this calcitonin-induced beta-endorphin release has not always been observed. These different results are discussed, and a possible implication of sex and/or calcitonin dose employed has been examined. We conclude that the analgesic effects of calcitonin are multifactorial, and beta-endorphin plays its own specific role.

Analgesics↗
PubMed1993

Inositol lipid-mediated intranuclear signalling: a comparative analysis of in vivo labelling in interferon alpha-sensitive and -resistant Daudi lymphoma cells.

Changes in inositol lipid and diacylglycerol metabolism have been analysed in Daudi lymphoma cells treated up to 24 h with human DNA recombinant interferon alpha. Results showing a different response of nuclear phosphoinositides and diacylglycerol, compared to whole cells, suggest that the intranuclear signalling system activated by interferon in Daudi cells involves nuclear inositol lipid metabolism. A well-characterized clone of Daudi cells selected for resistance to the antiproliferative action of interferon provided controls for the specificity of results.

Adolescent↗
PubMed1993

Evidence for nuclear phosphoinositidase C activity in the antiproliferative signals produced by interferon in Burkitt lymphoma cells.

The influence of interferon alpha on nuclear phosphoinositidase C (PIC) in Daudi cells has been analysed. Results showed an early increase of PIC activity detectable within 90 min of interferon treatment concomitant with an increase of diacylglcerol (DAG) levels. Since the interferon-induced DAG production is not modified by the addition of propranolol, a compound known to inhibit production of DAG from phosphatidylcholine hydrolysis, it is suggested that the interferon antiproliferative signal is transduced into the nucleus via the inositol lipid pathway. A parallel analysis performed on intact cells showed a rapid inhibition of PIC activity accompanied by an increase of DAG level thus suggesting that interferon-generated signals at plasma-membrane level use pathways different from that of inositol lipids. A selected clone of Daudi cells resistant to interferon action provided a control for specificity of results.

Burkitt Lymphoma↗
PubMed1993

Sex hormones and sex hormone-binding globulin in males with chronic viral hepatitis during recombinant interferon-alpha 2b therapy.

The effect of long-term treatment with recombinant interferon-alpha 2b (IFN-alpha 2b) on luteinizing hormone (LH), testosterone, free testosterone, and sex hormone-binding globulin (SHBG) was evaluated in 7 male patients suffering from chronic viral hepatitis. The drug was given three times a week for 6 months in a single standard dose of 3 x 10(6) units. Hormone evaluations were performed in basal conditions and every 2 months for 12 months. Serum testosterone values decreased after IFN treatment, reaching the lowest levels at the 6th month. However, testosterone values did not fall below the normal range. Serum SHBG concentrations, which were above the normal range in basal conditions, also decreased after IFN. Serum-free testosterone and LH concentrations did not change during IFN therapy. IFN-alpha 2b at the dose and schedule employed was not responsible for any measurable imbalance in male sex hormones.

Adult↗
PubMed1993

Nucleolar morphological rearrangement related to transcriptional and replicative state in Burkitt lymphoma cells.

The specific silver staining of nucleolar region organizers was applied to Daudi lymphoma control and interferon alpha-treated cells. Isolated nuclei from control and treated samples were used for the kinetic analysis of in vitro RNA and DNA synthesis. Results have shown that interferon treatment induces a reduction of the transcriptional and replicative activities within 90 min. Concomitant to these results is the modification of the organization of nucleoli. Intensity and distribution of silver grains are, in fact, different in treated cells nucleoli as compared to those of controls. Thus, the number and the arrangement of granules could be related to the functional state of the cells suggesting that the transient cascade of interferon-generated signals involves also modulation of nucleolar structure and function in accordance with the hypothesis of a relationship of cell proliferation rate to silver-stained nucleolar protein quantity.

Amanitins↗
PubMed1993

Relationship between nuclear ribonucleoprotein arrangement and cell proliferation in Burkitt lymphoma cells.

The presence of body-like structures in nuclei from interferon alpha-treated Daudi cells has been shown on the ultrastructural level, by the use of different staining methods. The degree of their rearrangement in the nucleoplasm seems to be dependent on the time of interferon treatment. Since this morphological evidence has been found to be preceded by a slowing down of RNA transcriptional machinery early upon the interferon administration, it is speculated that interferon generated signals might lead to RNP granule accumulation in the nucleus and a consequent arrangement into defined structures.

Burkitt Lymphoma↗
PubMed1993

[Evaluation of bronchiectasia with AMBER and high-resolution computerized tomography. Prospective study of a group of 50 patients].

The authors compared the diagnostic value of AMBER and HRCT in the evaluation of bronchiectasis. A series of 50 patients with conventional X-ray findings suggestive of this condition (increased pulmonary markings, loss of pulmonary volume and segmental cysts) were submitted to HRCT. In all the patients with bronchiectasis (25/50), AMBER showed increased pulmonary markings in one or more localizations, while loss of pulmonary volume was observed in 22 cases and segmental cysts in 8. The positive predictive value (PPV) of these findings was 50% for increased markings, 59% for the loss of pulmonary volume, 64% for the association of the former two signs and finally 100% for segmental cysts. The false-positive cases were due to bronchial wall thickening and to areas of peribronchial fibrosis. On the basis of their findings, the authors conclude that, except for the finding of segmental cysts, AMBER does not allow the unquestionable diagnosis of bronchiectasis to be made due to its low PPV (64%) and that further studies with HRCT are therefore required.

Bronchiectasis↗
PubMed1993

Phorbol ester induces changes in the synthesis of nuclear polyphosphoinositides and expression of terminal deoxynucleotidil transferase (TdT) in nuclei of KM-3 cells.

Terminal deoxynucleotidyl Transferase (TdT) play an essential role in the immune system differentiation. KM-3 cells are lymphoblastoid cells expressing the TdT and when induced to differentiate by phorbol ester (PMA) they loose this enzyme. Therefore, because of the suggested involvement of polyphosphoinositide in controlling the nuclear events it has been analyzed the phosphorylation of nuclear polyphosphoinositides during KM-3 differentiation. When the differentiated state is reached the phosphorylation level of PIP2 increases in isolated nuclei and this is accompanied by a concomitant decrease of PIP and PA, hinting at a correlation between polyphosphoinositide metabolism and TdT expression.

Cell Differentiation↗
PubMed1993

Sumatriptan does not affect vasopressin secretion in humans.

The aim of the study was to investigate the effects of a new serotoninergic drug, sumatriptan, on arginine vasopressin secretion in humans. Plasma vasopressin concentrations were determined in eight healthy volunteers, before and after administration of 6 mg of sumatriptan, or placebo. No changes in hormone levels were found after sumatriptan or placebo administration. The results suggest that in humans serotoninergic mechanisms, which modulate vasopressin secretion, do not involve the serotonin receptor activated by sumatriptan.

Adult↗
PubMed1992

The control of cellular shape and motility. Mg2+ and tropomyosin regulate the formation and the dissociation of microfilament bundles.

At pH 7.14 and 37 degrees C, in 7.2% (w/v) poly(ethylene glycol) 6000, tropomyosin-regulated actin filaments are converted into filament bundles by increasing the free Mg2+ concentration to 1.7-2.0 mM. When free Mg2+ concentration is decreased below 1.7 mM, bundles dissociate back into tropomyosin-regulated actin filaments. Pure actin filaments are insensitive to this mechanism of control and are found as filament bundles in all the range of free Mg2+ concentrations tested (1.37-2.2 mM). The mechanism of regulation described above is likely to operate in the cell, where the concentration of free Mg2+ is linked to the energy charge of the adenine nucleotide system.

Actin Cytoskeleton↗
PubMed1992

Interferon-mediated intracellular signalling. Modulation of different phospholipase activities in Burkitt lymphoma cells.

The effect of interferon-alpha on Daudi lymphoma cells either sensitive or resistant to the action of this cytokine has been analysed in terms of phospholipase C (PLC) and D (PLD) activities. Results have shown a combined modulation of PIP2-specific phospholipase C and phospholipase D. In particular, a decreased activity of PIP2-specific PLC has been found, concomitant to a PLD-mediated phosphatidylcholine hydrolysis, suggesting that the intracellular signalling activated by interferon in Daudi cells involves a phospholipase D/phosphohydrolase pathway.

Burkitt Lymphoma↗
PubMed1992

Regulation of pag gene expression in Bacillus anthracis: use of a pag-lacZ transcriptional fusion.

The production of protective antigen (PA), the common component of the two anthrax toxins, is influenced by the environment. In order to examine factors involved in its regulation, a transcriptional fusion between the promoter region of the PA gene (pag) and the lacZ gene was constructed and introduced into Bacillus anthracis Sterne. Activity of the pag promoter was followed by measuring beta-galactosidase activities under various growth and medium conditions. Expression from the pag promoter was observed throughout exponential-phase and was maximal in early stationary phase. The activity of the pag promoter was stimulated by the addition of glucose in the medium.

Antigens, Bacterial↗
PubMed1992

A combined ultrastructural approach to the study of nuclear matrix thermal stabilization.

Using mouse erythroleukaemia cells and different ultrastructural techniques, the morphology was investigated of the nuclear matrix obtained after incubation at 37 degrees C of isolated nuclei. If purified nuclei were heated for 45 min at 37 degrees C, the final matrix exhibited well-recognizable nucleolar remnants, an inner network and a peripheral lamina. Without such incubation only the peripheral lamina was seen surrounding homogeneous, finely granular material. Similar results were obtained with both araldite-embedded and freeze-fractured nuclear matrices, although in the latter case the loose granular material was not evident. Observations of araldite-embedded, heat-treated nuclei revealed clumping of heterochromatin in small, very electron-dense masses with large interchromatin spaces. These ultrastructural aspects were even more striking in freeze-fractured nuclei. Cytochemical matrix analysis by osmium-amine staining for nucleic acids and DNase-gold labelling for DNA localization demonstrated that also matrix residual nucleic acids, mostly RNA, are stabilized by heat exposure of isolated nuclei. The results demonstrate that the morphology of heat-stabilized nuclear matrix is not artefactually affected during the preparation for conventional electron microscopy and suggest a possible involvement of nucleic acids in the heat-induced stabilization of the nuclear matrix.

Animals↗
PubMed1992

The impairment of natural killer function in the healthy aged is due to a postbinding deficient mechanism.

In order to study the fine mechanisms that underlie the impairment of non-MHC-restricted cytolytic activity which occurs during human aging, we examined by multiparametric flow cytometry the binding and lytic activities of human natural killer cells. The flow analysis revealed a striking increase of the CD16+8- subset, together with a significant decrease of CD8bright cells and total T cells (CD3+). Aging had no influence on the CD8dim subset. The total lytic activity expressed by PBL as well as their binding efficiency to K562 targets were moderately but not significantly increased in the elderly. In contrast, the cytotoxicity of the single target-bound natural killer cell (i.e., lytic efficiency) was deeply impaired in aged subjects, suggesting that the NK functional impairment observed in aging is located at postbinding level.

Adult↗