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M Capri

Publications and source records attributed to M Capri.

35 records · Page 2Linked to original sources
PubMed1995

Human natural killer cytotoxic activity is not affected by in vitro exposure to 50-Hz sinusoidal magnetic fields.

Epidemiological studies have suggested, but not demonstrated, a role of exposure to 50/60-Hz magnetic fields in increasing cancer risk in man (workers and the general population). A possible target of magnetic fields is the immune system. In particular, it is known that an important defence against cancer is represented by natural killer (NK) cells capable of killing cancer cell targets. To test this hypothesis, human NK cells, stimulated or not with phytohaemagglutinin or interleukin 2, were exposed to 50-Hz sinusoidal magnetic fields before or during the cytotoxicity test, and then mixed with a variety of target cancer cell lines (Daudi, Raji, U937, H14, IGROV, SW626, K562, HL60). The experiments were performed in two laboratories (Rome and Modena) by means of two different exposure systems. The results of both laboratories suggest that 50-Hz sinusoidal magnetic fields with flux densities up to 10 mT do not affect the cytotoxic activity of human NK cells.

Adult↗
PubMed1994

Apoptosis and spermatogenesis: evidence from an in vivo model of testosterone withdrawal in the adult rat.

The seminiferous epithelium is a highly proliferating tissue in which germ cell "degeneration" is a constant feature. Recent data based on morphological analysis have shown that spontaneously dying germ cells display some characteristics of apoptosis. In order to evaluate the molecular signals controlling the phenomenon, adult male rats were studied after in vivo treatment with ethane dimethane sulphonate, an agent which leads to testosterone withdrawal by a selective destruction of Leydig cells. DNA fragmentation by agarose gel electrophoresis and cell DNA content by flow cytometry after propidium iodide staining were used to evaluate and quantify apoptosis in the testis. Despite the simultaneous presence of cells with different ploidies, the present data suggest that testosterone withdrawal induces death by apoptosis and that this phenomenon is particularly evident in haploid germ cells. Thus, this study support the involvement of testosterone in regulating programmed cell death, beside cell proliferation and differentiation, during spermatogenesis.

Animals↗
PubMed1994

3-Aminobenzamide induces cytoskeleton rearrangement in M14 melanoma cells.

3-aminobenzamide (3-ABA) is an inhibitor of poly-ADP-ribose-polymerase, an enzyme involved in numerous subcellular processes including cell death. With the aim of contributing to clarify the mode of action of the drug, which is still poorly understood, its effects on cultured melanoma cells M14 have been assessed. In particular, an impairment of cell growth accompanied by the formation of long and numerous dendritic-like protrusions has been detected. This finding appears to be due to a specific effect of the drug on some cytoskeletal elements and could be associated with its differentiating capability. This finding, together with previous data from our group--Biochem. Biophys. Res. Commun., (1994) 199, 525-530 and 1250-1255--suggests that cytoskeleton is an important target of 3-ABA.

Benzamides↗
PubMed1994

D-ribose and deoxy-D-ribose induce apoptosis in human quiescent peripheral blood mononuclear cells.

In previous papers we reported that D(-)-ribose and 2-deoxy-D-ribose, which rank at the top among reducing sugars, kill a variety of human and animal cells and cell lines. Here we demonstrate that these two sugars induce apoptosis in human quiescent peripheral blood mononuclear cells which are relatively insensitive to apoptosis. Apoptosis was assessed by morphological changes, DNA fragmentation by agarose gel electrophoresis and the appearance of an hypodiploid peak by flow cytometry. 2-deoxy-D-ribose was more potent than D(-)-ribose and apoptosis was evident from 48 hours of culture onwards. 2-deoxy-D-ribose-induced apoptosis was inhibited by N-acetyl-L-cysteine, suggesting that glutathione metabolism and/or oxidative stress are involved in this type of apoptosis. Thus, D(-)-ribose and 2-deoxy-D-ribose can be useful tools to study the cellular and molecular events of apoptosis in human quiescent lymphocytes.

Acetylcysteine↗
PubMed1994

Mitochondrial modifications during rat thymocyte apoptosis: a study at the single cell level.

Apoptosis is an active type of cell death, occurring under several physiological and pathological conditions. The role of cellular organelles such as mitochondria in this process is still an open question. We recently described a new method to measure mitochondrial membrane potential in intact cells using flow cytometry. Using this method we studied alterations of mitochondrial membrane potential in a classical model of apoptosis, i.e., dexamethasone-treated rat thymocytes. Moreover, apoptosis induced by heat shock was also studied in the same cells. Mitochondria are functionally intact during the early phases of apoptosis, when DNA fragmentation occurs, whereas early alteration in their potential and mass takes place after DNA damage. According to flow-cytometric analysis, the presence of a hypodiploid peak, an index of nuclear DNA loss, predates depolarization of mitochondrial membrane and decrease of mitochondrial mass. Loss of plasma membrane integrity, which indicates cell death and is revealed by the permeability to propidium iodide, eventually follows. All these phenomena are more evident in dexamethasone-treated cells than in heat-shocked cells. Thus, in these types of apoptosis the involvement of mitochondria is apparently not a primary event.

Animals↗
PubMed1993

Exposure to low frequency pulsed electromagnetic fields increases interleukin-1 and interleukin-6 production by human peripheral blood mononuclear cells.

The exposure of human peripheral blood mononuclear cells to extremely low frequency pulsed electromagnetic fields (PEMFs) increased both the spontaneous and the PHA- and TPA-induced production of interleukin-1 (IL-1) and IL-6. Our results suggest that cells of the monocytic lineage, which are good producers of both IL-1 and IL-6, can be important cellular targets for PEMFs. Taking into account that these cytokines are among the most pleiotropic ones, these data can help us understand the previous reported effects of PEMFs on the proliferation of human lymphocytes and the effects exerted by such fields on cartilage and bone cells, whose physiological activity is highly dependent on IL-1 and IL-6.

Adult↗
PubMed1993

50 Hz AC sinusoidal electric fields do not exert genotoxic effects (micronucleus formation) in human lymphocytes.

Electromagnetic fields produce a variety of effects in several biological systems, including human peripheral blood lymphocytes. A great concern exists regarding possible carcinogenic effects in subjects exposed environmentally to such fields in the vicinity of power lines and electric domestic appliances. Using human lymphocytes from 33 healthy donors and a sensitive cytogenetic method, the cytokinesis-block micronucleus assay, we have demonstrated that the exposure to 50-Hz AC sinusoidal electric fields over a wide range of intensities (0.5-10 kV/m in air) does not increase the spontaneous frequency of micronuclei. Moreover, these fields did not affect the mitomycin-C-induced micronucleus formation, suggesting that they did not exert any synergistic or antagonistic effect.

Adult↗
PubMed1992

Inhibition of apoptosis by zinc: a reappraisal.

Apoptosis--or programmed cell death--is an active type of cell death, occurring in several pathophysiological conditions. One of the most important characteristics of apoptosis is that cell death is preceded by DNA fragmentation, consequent to the activation of nuclear calcium- and magnesium-dependent endonuclease(s). DNA fragmentation can be inhibited by zinc ions. By using several techniques, such as DNA agarose gel electrophoresis, cytofluorimetric analysis of DNA content and of cell cycle, 3H-thymidine incorporation and trypan blue dye exclusion test, we show that zinc, despite completely inhibiting DNA fragmentation and the consequent loss of nuclear DNA content, does not protect rat thymocytes from spontaneous or dexamethasone-induced death. Our data also suggest that DNA fragmentation, although characteristic, is not a critical event for thymocyte death of apoptotic type.

Animals↗
PubMed1992

The yemanuclein-alpha: a new Drosophila DNA binding protein specific for the oocyte nucleus.

The Drosophila yG 4.5 gene (now called yemanuclein-alpha gene), which maps at 98F, is a member of the yema gene cluster isolated in a search for differentially expressed maternal genes. The yemanuclein-alpha transcript (formerly yT 4.5) is specifically expressed in the female germ cells at early oogenic stages and displays a graded distribution along the antero-posterior axis of the oocyte. These provocative features are reminiscent of that of K10, bicoid and Bicaudal-D gene transcripts and lead us to hypothesize that the yemanuclein-alpha gene plays a key role in egg organization. We show in the present work that the yemanuclein-alpha is a nuclear protein highly specific for the oocyte nucleus. The sequence analysis of the 5696 bp EcoRI fragment containing the yemanuclein-alpha gene, and of 5 overlapping cDNAs, reveals a 3006 nucleotides long open reading frame (ORF) flanked by long untranslated 5' and 3' sequences. This ORF predicts a 109,215 kDa protein which is basic (pHi: 8.57), and serine rich (12.08%). It contains a 40 amino acid acidic domain in the first third of the protein with a potential alpha-helix organization; this domain has some similarity with the nucleolin acidic domain. Parts of the yemanuclein-alpha sequence are likely to form secondary structures known to interact with DNA. We demonstrate the DNA binding activity of the yemanuclein-alpha by affinity chromatography experiments. Our data indicate that the yemanuclein-alpha shares some of the features which are characteristic of genuine transcriptional activators.

Amino Acid Sequence↗
PubMed1990

Expression in the central nervous system of a subset of the yema maternally acting genes during Drosophila embryogenesis. Post-embryonic expression extends to imaginal discs and spermatocytes.

The yema gene region of Drosophila melanogaster is a cluster of maternally acting genes isolated in differential screens. At least ten transcripts are encoded by the yema gene region; most of them are produced by independent transcription units (eight different transcription units). Using RNA dot-blot analysis and in situ hybridization to tissue sections, we have realized a comprehensive survey of the temporal and spatial expression of the yema transcripts. All these transcripts are maternally expressed. Five of them display a strict maternal expression. They are found exclusively in the female germ line (nurse cells and oocyte). These transcripts are still present in the embryo as maternal information. However, a subset of the yema genes also shows an embryonic and a post-embryonic expression. Interestingly, this expression is essentially restricted to the central nervous system (CNS) throughout the fly development, to the larval and pupal imaginal discs and to a subset of cells in the male gonad, the spermatocytes. Strikingly, these expression sites mainly contain proliferating and/or differentiating cells.

Animals↗
PubMed1988

Isolation of developmentally regulated genes in Drosophila melanogaster.

We used a molecular approach to search for maternally expressed genes in Drosophila melanogaster. The relative merits of differential and competition screens were analyzed in a series of reconstruction experiments using either purified phage plaques or derivative DNA sequences. In the course of this study, we isolated 5 clones whose RNA level varies during early embryogenesis. Three gastrula differential clones, b4, b8 and d3, are present in numerous copies in the genome; clone b4 hybridizes with the copia-like B104 repetitive sequence described by Scherer et al. We also isolated 2 maternally-expressed genes, not previously identified in either classical genetic or similarly molecular-based screens. These clones, b11 and d6, map at cytogenetic positions 98F and 4F respectively, on the polytene chromosome map.

Animals↗
PubMedDate not supplied

Effect of zinc ions on apoptosis in PBMCs from healthy aged subjects.

Immunosenescence features, such as thymic involution, alteration of T-cell repertoire, autoimmunity and accumulation of memory/effector T cells, may be the result, at least in part, of a zinc deficiency, which is often observed during ageing. Zinc, as essential trace element, affects the immune system function and it is an important regulator of apoptosis of immune cells. In this study we addressed the question whether zinc supplementation in vitro at physiological doses can affect spontaneous and oxidative stress-induced apoptosis in peripheral blood mononuclear cells from subjects of three different age groups: young (mean age 28 years), old (mean age 72 years) and nonagenarians. We studied different parameters related to apoptosis (phosphatydilserine exposure, mitochondrial membrane potential, caspase 3 cleavage) and we found that zinc, while decreasing spontaneous apoptosis, can increase oxidative stress-induced apoptosis in an age-related fashion, being this effect more evident in nonagenarians than in old or young subjects. In particular, zinc can increase late apoptosis/necrosis, a phenomenon that could trigger unnecessary inflammation in vivo. We surmise that these age-associated alterations in susceptibility to apoptosis may be due to a different effect of zinc on T cell subsets, that are altered in very old people, and finally that the zinc deficiency, which is often observed in aged subjects, could be a compensatory mechanism to counteract the inflammatory status of the elderly.

Adult↗
PubMedDate not supplied

Deoxyribonucleic acid of Cancer pagurus. IV. Elution behaviour on hydroxyapatite chromatographic column.

Fractionation of native DNA on hydroxyapatite columns depends, when flat and continuous gradients are used, on the base composition, GC-rich fractions being eluted in the first fractions. Crab satellite DNA behaves abnormally : the first eluted fractions are enriched in poly d(A-T).d(A-T) instead of GC as usual. It amy be suggested that these differences in the behaviour could be attributed to the fact that the secondary structure of crab DNA satellite is different from the secondary structure of the main DNA component.

Animals↗