Biomedical subjects

F Bersani

Publications and source records attributed to F Bersani.

At least 19 recordsLinked to original sources

PubMed2006

Effects on apoptosis and reactive oxygen species formation by Jurkat cells exposed to 50 Hz electromagnetic fields.

The effect of exposure to 50 Hz electromagnetic field on a human T-leukaemia cell line (Jurkat) was investigated by evaluating the reactive oxygen species (ROS) production and apoptosis, both spontaneous and induced by a specific anti Fas/CD95 monoclonal antibody (anti-Fas). Our results suggest that 1 h intermittent (5 min field on/10 min field off) exposure does not affect ROS formation, while a slight but statistically significant decrease of both spontaneous and anti-Fas-induced apoptosis was observed.

Apoptosis↗

PubMed2004

Various effects on transposition activity and survival of Escherichia coli cells due to different ELF-MF signals.

Previous assays with weak sinusoidal magnetic fields (SMF) have shown that bacteria that had been exposed to a 50 Hz magnetic field (0.1-1 mT) gave colonies with significantly lower transposition activity as compared to sham-exposed bacteria. These experiments have now been extended by using a pulsed-square wave magnetic field (PMF) and, unexpectedly, it was found that bacteria exposed to PMF showed a higher transposition activity compared to the controls. The increase of the transposition activity was positively correlated with the intensity of the magnetic fields (linear dose-effect relation). This phenomenon was not affected by any bacterial cell proliferation, since no significant difference was observed in number and size of PMF-exposed and sham-exposed colonies. In addition, the cell viability of E. coli was significantly higher than that of the controls when exposed to SMF, and lower than that of the controls when exposed to PMF. Under our experimental conditions it was shown that exposure to PMF stimulates the transposition activity and reduces cell viability of bacteria, whereas exposure to SMF reduces the transposition mobility and enhances cell viability. These results suggest that the biological effects of magnetic fields may critically depend on the physical characteristics of the magnetic signal, in particular the wave shape.

Cell Survival↗

PubMed2004

1800 MHz radiofrequency (mobile phones, different Global System for Mobile communication modulations) does not affect apoptosis and heat shock protein 70 level in peripheral blood mononuclear cells from young and old donors.

PURPOSE: To study if prolonged in vitro exposure to 1800MHz radiofrequency (RF) could exert an effect on human peripheral blood mononuclear cells (PBMC) from young and elderly donors by affecting apoptosis, mitochondrial membrane potential and heat shock protein (HSP) 70 levels. MATERIALS AND METHODS: Endpoints were analysed in the presence or absence of the apoptosis-inducing agent 2-deoxy-D-ribose. Three different signal modulations typical of the Global System for Mobile communication (GSM) system were applied. The modulations are widely used in mobile telephony (GSM Basic, discontinuous transmission [DTX] and Talk) at specific absorption rates of 1.4 and 2.0 W kg(-1). RESULTS: In all conditions and for all endpoints tested, there was no significant difference between RF- and sham-exposed cells. CONCLUSION: 1800MHz RF could not induce apoptosis by itself or affect the apoptotic phenomenon when induced by an apoptotic agent. Moreover, RF did not modify the mitochondrial functionality and the expression of HSP 70.

Adult↗

PubMed2003

Extremely low frequency magnetic fields affect transposition activity in Escherichia coli.

The aim of this study was to verify whether extremely low frequency (ELF) magnetic fields (MF) could affect transposition activity like some environmental stress factors such as heat shock or UV irradiation. Using an Escherichia coli Lac Z(-) strain transformed with a plasmid containing a Tn 10 derivative element expressing beta-galactosidase only after transposition, it was possible to determine the events of transposition evaluating the rate at which the colonies developed dark coloured papillae (Lac Z(+)). We found that those bacteria that had been exposed for a long time (58 h) to a 50 Hz low intensity MF (0.1-1 mT) gave colonies with significantly lower transposition activity compared to sham-exposed bacteria. Such reduction in transposition activity was positively correlated to the intensity of the MF, in a dose-effect manner. This phenomenon was not affected by bacterial cell proliferation, since no significant differences were observed in number, diameter and perimeter between sham-exposed and MF-exposed colonies.

Cell Cycle↗

PubMed2003

A four coil exposure system (tetracoil) producing a highly uniform magnetic field.

We propose a magnetic field exposure system (tetracoil) for in vitro and in vivo experiments, composed of two couples of circular coils satisfying a spherical constraint, whose characteristics are chosen in order to maximize the uniformity region of the magnetic field. Analytical calculations and computer simulations show that our system, as compared to the other most largely used magnetic field exposure systems, represents an optimal compromise in terms of field uniformity, accessibility for biological experiments, and ratio between overall dimension and uniformity region.

Computer Simulation↗

PubMed2003

Lack of genotoxic effects (micronucleus induction) in human lymphocytes exposed in vitro to 900 MHz electromagnetic fields.

In the present study, we investigated the induction of genotoxic effects in human peripheral blood lymphocytes after exposure to electromagnetic fields used in mobile communication systems (frequency 900 MHz). For this purpose, the incidence of micronuclei was evaluated by applying the cytokinesis-block micronucleus assay. Cytotoxicity was also investigated using the cytokinesis-block proliferation index. The experiments were performed on peripheral blood from 20 healthy donors, and several conditions were tested by varying the duration of exposure, the specific absorption rate (SAR), and the signal [continuous-wave (CW) or GSM (Global System of Mobile Communication) modulated signal]. The following exposures were carried out: (1) CW intermittent exposure (SAR = 1.6 W/kg) for 6 min followed by a 3-h pause (14 on/off cycles); (2) GSM signal, intermittent exposure as described in (1); (3) GSM signal, intermittent exposure as described in (1) 24 h before stimulation with phytohemagglutinin (8 on/off cycles); (4) GSM signal, intermittent exposure (SAR = 0.2 W/kg) 1 h per day for 3 days. The SARs were estimated numerically. No statistically significant differences were detected in any case in terms of either micronucleus frequency or cell cycle kinetics.

Adult↗

PubMed2000

Elf-pulsed magnetic fields modulate opioid peptide gene expression in myocardial cells.

OBJECTIVES: Magnetic fields have been shown to affect cell proliferation and growth factor expression in cultured cells. Although the activation of endorphin systems is a recurring motif among the biological events elicited by magnetic fields, compelling evidence indicating that magnetic fields may modulate opioid gene expression is still lacking. We therefore investigated whether extremely low frequency (ELF) pulsed magnetic fields (PMF) may affect opioid peptide gene expression and the signaling pathways controlling opioid peptide gene transcription in the adult ventricular myocyte, a cell type behaving both as a target and as a source for opioid peptides. METHODS: Prodynorphin gene expression was investigated in adult rat myocytes exposed to PMF by the aid of RNase protection and nuclear run-off transcription assays. In PMF-exposed nuclei, nuclear protein kinase C (PKC) activity was followed by measuring the phosphorylation rate of the acrylodan-labeled MARCKS peptide. The effect of PMF on the subcellular distribution of different PKC isozymes was assessed by immunoblotting. A radioimmunoassay procedure coupled to reversed-phase high performance liquid chromatography was used to monitor the expression of dynorphin B. RESULTS: Here, we show that PMF enhanced myocardial opioid gene expression and that a direct exposure of isolated myocyte nuclei to PMF markedly enhanced prodynorphin gene transcription, as in the intact cell. The PMF action was mediated by nuclear PKC activation but occurred independently from changes in PKC isozyme expression and enzyme translocation. PMF also led to a marked increase in the synthesis and secretion of dynorphin B. CONCLUSIONS: The present findings demonstrate that an opioid gene is activated by myocyte exposure to PMF and that the cell nucleus and nuclear embedded PKC are a crucial target for the PMF action. Due to the wide ranging importance of opioid peptides in myocardial cell homeostasis, the current data may suggest consideration for potential biological effects of PMF in the cardiovascular system.

Analysis of Variance↗

PubMed1999

Micronucleus frequency and cell proliferation in human lymphocytes exposed to 50 Hz sinusoidal magnetic fields.

In the present study micronucleus induction and cell proliferation in human peripheral blood lymphocytes cultured in vitro and exposed to 50 Hz sinusoidal magnetic fields for 72 h at different intensities (1.0, 0.75, 0.5, 0.25, and 0.05 mT rms) were investigated. The results obtained from 42 healthy donors aged between 26 and 54 y indicate that, for the field intensities tested, no genotoxic effects were found, as assessed by the cytokinesis-block micronucleus assay. On the contrary, cell proliferation, evaluated by the cytokinesis-block proliferation index, was slightly affected by the field at the intensities tested.

Cell Division↗

PubMed1997

Intramembrane protein distribution in cell cultures is affected by 50 Hz pulsed magnetic fields.

Intramembrane proteins (IMP) represent a class of proteins located in the lipid bilayer of the cell membrane which function as ion channels, enzymes or receptors. Since it has been argued that biological effects of extremely low frequency (ELF) electromagnetic fields are mediated by plasma membrane. this work was designed to study the possible effects of 50 Hz pulsed magnetic fields (PMF) of the type used to stimulate bone repair, on the distribution of IMP in the plasma membrane of Swiss NIH 3T3 fibroblasts. Evaluations were based on the calculation of a distribution factor, which allows discrimination between random, regular and clustered distribution of IMP, in electron microscope images of freeze-fractured membranes. The results indicate that cells exposed to PMF for more than two hours have a significant clustering of the IMP distribution compared to control unexposed cells.

3T3 Cells↗

PubMed1996

Spontaneous and mitomycin-C-induced micronuclei in lymphocytes from subjects affected by Turner's syndrome.

Peripheral blood lymphocytes from 15 subjects affected by Turner's syndrome (TS) and aged between 2 and 24 years (mean age 10.40 +/- 6.25) were tested to evaluate the spontaneous and Mitomycin-C-induced (MMC) micronucleus (MN) frequency. A group of 15 healthy subjects, in the same range of age (mean age 14.67 +/- 8.30), was also tested as control. As expected, statistically significant differences between spontaneous and MMC-induced MN were found either in TS and in healthy subjects. Unexpectedly, when the two groups of donors were compared, TS subjects showed a lower spontaneous and MMC-induced MN frequency, in comparison with healthy subjects. Cell proliferation kinetic and cytotoxicity were also measured applying the cytokinesis-block proliferation index (CBPI): the results show that MMC, at the employed concentration, does not induce cell cycle delay both in healthy and in TS donors. Whereas, when CBPI from TS and healthy donors were compared, a faster proliferation was found in TS patients in both untreated and MMC-treated cultures.

Adolescent↗

PubMed1996

CD45 isoforms expression on CD4+ and CD8+ T cells throughout life, from newborns to centenarians: implications for T cell memory.

CD4+ and CD8+ peripheral blood T lymphocytes show mutually exclusive expression of CD45RA or CD45R0, two isoforms of the common leukocyte antigen that seem to recognize so-called virgin/unprimed and memory/activated T cells. The expression of these isoforms has been studied by three colour cytofluorimetric analysis on CD4+ or CD8+ peripheral blood CD3+ cells from 22 healthy centenarians, analyzed in a context of 202 healthy donors 0-110 years old. An age-related unbalance of virgin and memory cells was found between CD4+ and CD8+ subsets. As expected, at birgh 95-99% of the CD3+ lymphocytes expressed the CD45RA isoform. A rapid increase of CD45R0+ cells was observed in the first 2-3 decades of life, this phenomenon being much more pronounced on CD4+ cells. Subsequently, the increase of the 'memory' compartment was much less rapid, so that in centenarians a consistent reservoire of CD45RA+ among CD4+ cells was still present (about 20%). In these exceptional individuals the percentage of CD45RA+ cells among CD8+ T lymphocytes was even higher (about 50%), and only slightly lower than that of young donors (about 55-60%). Thus, the main changes occurred at a different rate in CD4+ (about 20%). In these exceptional individuals the percentage of CD45RA+ cells among CD8+ T lymphocytes was even higher (about 50%), and only slightly lower than that of young donors (about 55-60%). Thus, the main changes occurred at a different rate in CD4+ and in CD8+ T cells, at an age of between 0 and 30 years, when the thymus is still functionally active. Interestingly, no difference in the usage of CD45 isoforms was observed within T cells bearing four different V beta-T cell receptor (TCR). The significance of this age-related unbalance is unknown. However, the presence of a great number of CD45RA+ T lymphocytes within the CD4+ and the CD8+ T cell subsets even in the peripheral blood of centenarians poses the problem of their origin (thymus? extrathymic sites?), of their functional role and of their lifespan. Moreover, the data on centenarians suggest that they may represent a very selected population where a slowing of immunosenescence occurs.

Adolescent↗

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

Lack of chromosomal aberration and micronucleus induction in human lymphocytes exposed to pulsed magnetic fields.

We exposed human peripheral blood lymphocyte cultures to 50 Hz pulsed magnetic fields (PMFs) in order to evaluate a possible genotoxic effect of such non-ionizing radiation. The genotoxic effect was evaluated in terms of both micronucleus (MN) induction and classical chromosomal aberrations (CA); the mitotic index (MI) was also calculated. Khalil and Qassem (1991) found chromosomal and chromatid breaks and mitotic delay in human lymphocytes exposed for 24, 48 and 72 h to a field with characteristics similar to those used in our laboratory. These data are in contrast with our results previously reported in terms of MN induction using the cytokinesis block method (Scarfi et al., 1991). In this study lymphocytes from five healthy human donors were examined with the above mentioned tests. No genotoxic effects and increased MI were found in exposed samples compared to the control ones, in agreement with our previous results.

Cells, Cultured↗

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

Lymphocytes and low-frequency electromagnetic fields.

Human lymphocytes have been used by several researchers to investigate the biological effect of electromagnetic fields (EMF). EMF modulate the response by lymphocytes to lectin stimulation. The size and direction of the effect depends both on the lymphocyte physiology and on the physical parameters characterizing the EMF. Lymphocytes have also been used to investigate the genotoxicity of EMF exposure.

Electromagnetic Fields↗

PubMed1991

Spontaneous and mitomycin-C-induced micronuclei in human lymphocytes exposed to extremely low frequency pulsed magnetic fields.

The cytokinesis block micronucleus method, a very sensitive cytogenetic assay, was used to ascertain the possible genotoxic effects of extremely low frequency pulsed magnetic fields in phytohemagglutinin-stimulated human lymphocytes cultures from 16 healthy donors. Four conditions were studied: i) lymphocytes not exposed to the field (control cultures); ii) lymphocytes exposed to the field; iii) lymphocytes treated with mitomycin-C and not exposed to the field; iv) lymphocytes treated with mitomycin-C and exposed to the field. Mitomycin-C-treated cultures were used as control for the micronucleus method, because it is known that mitomycin-C is a potent genotoxic agent, capable of inducing micronuclei. The frequency of micronuclei in field-exposed cultures was similar to the spontaneous frequency observed in control unexposed-cultures. Moreover, the exposure to pulsed magnetic fields did not affect the frequency of micronuclei induced by mitomycin-C, suggesting that, in the experimental conditions used, this kind of field neither affected the integrity of chromosomes nor interfered with the genotoxic activity of mitomycin-C.

Alkylating Agents↗

PubMed1991

Exposure to low-frequency pulsed electromagnetic fields increases mitogen-induced lymphocyte proliferation in Down's syndrome.

We previously reported that exposure of human mitogen-stimulated peripheral blood lymphocytes (PBL) to extremely low frequency pulsed electromagnetic fields (PEMFs) could restore the defective proliferative capability of PBL from aged subjects. The effects of exposure to PEMFs were studied in PBL from 25 patients with Down's syndrome (DS), a syndrome of premature aging characterized by precocious immune system derangement, including age-related defective PBL proliferative capability. PBL were stimulated with different doses of phytohemagglutinin, and cell proliferation was assessed by measuring the incorporation of tritiated thymidine. After PEMF-exposure, a significant increase in cell proliferation was observed in cells from DS children and young adults, but it was much more evident in PBL from relatively aged DS patients. The age-related effect of PEMFs on DS lymphocytes demonstrates that age must be considered a major variable when studies on DS are performed, and confirms that DS must be regarded as a syndrome of accelerated aging.

Adolescent↗