Monica Ballerini

Magnetic field effects on human lymphocytes

The results are discussed of a systematic investigation into the electromagnetic field (EMP) exposure consequences on human lymphocytes. These artificial fields have intensities comparable to the Earths magnetic field, and are used for exposures up to 4 days. Different and complementary techniques are used to safely assess the consequences of EMFs on the cells; in particular, morphology, metabolism, and population dynamics are investigated. The recourse to ultramicroscopy, pressure monitoring in sealed bottles, atomic mass spectroscopy, and cytofluorimetry techniques give good insight into the EMF-induced changes. A statistically significant deviation of irradiated samples with respect to control samples is reported. A critical analysis and a survey of similar experiments reported in the literature led us to examine the experimental setup with attention to the geometry of the irradiation system. Yeast cells were used as a model system to statistically test the different steps in the overall procedure, thanks to information gathered during a radiobiology experiment performed at the Rutherford Appleton Laboratory. Finally, the role of different magnetic field detectors in the reproducibility of the experiments is carefully discussed.

Focused ion beams and life science applications: cell tomography and biomachining at ultrahigh resolution

A new technique of Focused Ion Beam (FIB) microscopy- nanomachining is proposed for life sciences. Its performances are compared with those of currently available ultramicroscopy apparatuses. Ultra-high resolution tridimensional tomography can be performed on whole cells without preparation. This can be achieved by sequentially etching layers of material and subsequently viewing the result of the operation under a different perspective. Very fast imaging times (minutes) allow quasi real time microscopy. The complementary technique of nano-biology can be performed on the same apparatus. The use of the ion beam allows to imaging both the surface and the inner part of the sample along any desired plane that can be chosen while the observation is on.

An ensemble of new techniques to study soft-X-ray-induced variations in cellular metabolism

An ensemble of new techniques has been developed to study cell metabolism. These include: CO2 production monitoring, cell irradiation with soft X rays produced with a laser-plasma source, and study of oscillations in cell metabolic activity via spectral analysis of experimental records. Soft X-rays at about 0.9 keV, with a very low penetration in biological material, were chosen to produce damages at the metabolic level, without great interference with DNA activity. The use of a laser-plasma source allowed a fast deposition of high doses. Monitoring of CO2 production allowed us to measure cell metabolic response immediately after irradiation in a continuous and non invasive way. Also a simple model was developed to calculate X-ray doses delivered to the different cell compartments following a Lambert-Bouguet–Beer law. Results obtained on Saccharomyces cerevisiae yeast cells in experiments performed at Rutherford Appleton Laboratory are presented.

Magnetic field effects on human lymphocytes : methodological assessments and experimental evidences

The results are discussed of a systematic investigation on the electromagnetic field exposure consequences on human lymphocytes. These artificial fields have intensities comparable with the Earth magnetic field one, and are used for exposures up to 4 days. Different and complementary techniques are used to safely assess the consequences of ElectroMagnetic Fields (EMF) on the cells; in particular morphology, metabolism and population dynamics are investigated. The recourse to ultra microscopy, pressure monitoring in sealed bottles, atomic mass spectroscopy. Far IR Fourier Transform and cytofluorimetry techniques give a good insight in the EMF induced changes. A statistically significant deviation of irradiated samples with respect to the control ones are reported. A critical analysis and a survey of similar experiments reported in literature lead us to the exam of the experimental set up with attention to the geometry of the irradiation system. Finally the role of different magnetic field detectors in the reproducibility of the experiments will be carefully discussed.

Microscopy characterization of doped fibers

The use of the Soft X-ray Contact Microscopy technique is discussed as a possible new tool to get information on dopant distribution in the core of single-mode optical fibers with 50 nm spatial resolution.

Yeast and mammalian metabolism continuous monitoring by using pressure recording as an assessment technique for xenobiotic agent effects

Our work is devoted to the study of Saccharomyces cerevisiae and human lymphocytes cellular metabolism in order to develop a reference model to assess biological systems responses to chemical or physical agents exposure. CO2 variations inside test-tubes are measured by differential pressure sensors; pressure values are subsequently converted in voltage. The system allows to test up to 16 samples at the same time. Sampling manages up to 100 acquisitions per second. Values are recorded by a data acquisition card connected to a computer. This procedure leads to a standard curve (pressure variation versus time), typical of the cellular line, that describe cellular metabolism. The longest time lapse used is of 170 h. Different phases appear in this curve: an initial growth up to a maximum, followed by a decrement that leads to a typical depression (pressure value inside the test-tubes is lower than the initial one) after about 35 h from the beginning of yeast cells. The curve is reproducible within an experimental error of 4%. The analysis of many samples and the low cost of the devices allow a good statistical significance of the data. In particular as a test we will compare two sterilizing agents effects: UV radiation and amuchina.

Mass spectrometry technique for the analysis of metabolic changes in soft x-ray-irradiated cells

Mass spectrometry identifies atomic and molecular species and relative concentrations in a given atmosphere. The analysis of the composition and of the atmosphere variations in a batch system, that contains a suspension of yeast cells or lymphocytes, allows to identify and to track cell metabolic processes. Such a technique has proven to be efficient in radiobiology experiments to investigate soft X- ray non-nuclear damages, as complimentary to other physical and chemical assessments.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Differential two-color x-ray radiobiology of membrane/cytoplasm in yeast cells and lymphocytes

An overall approach into the differential investigation of membrane/cytoplasm related metabolism and of cell-cycle of yeast cells after two color soft X-ray irradiation is presented; the soft X-rays being generated in trains of picosecond pulses by laser-plasma interaction. The two color X-ray differential technique is based on the generation of approximately 0.6 KeV X-rays which are deposited only in the membrane-wall complex switching off the anaerobic (fermentative) activity of yeast cells and on the generation of approximately 1.2 KeV X-rays which are mainly deposited in the cytoplasm, mitochondria and nucleus of yeast cells, mainly affecting the aerobic metabolism. A synergetic analysis of the metabolism is discussed, mainly founded on the recording of different correlated metabolic parameters, both on-line and delayed. Among the relevant access, pressure monitoring in batch samples acquire a dominant role allowing the identification of metabolic oscillation, that represent a marker of physical and chemical actions performed on the samples at different times. The experience acquired on yeast cells metabolism is being used to investigate lymphocytes metabolism and the related oscillatory properties of relevant enzymatic complexes. Actually even if it is not exactly the same as the mammalian situation, it should really propel the whole field forward.

Delayed luminescence technique: a probe for vital processes in biological systems

Delayed Luminescence is a well established technique based on the illumination of biological sample and on the subsequent count of the number of photons re-emitted by the sample after the light source has been switched off together with their spectral distribution. Investigations have been performed on yeast cells and algae so that correlations can be established between biological activities and physical parameters of the samples. Moreover nonlinear mechanisms of interaction between optical fields and cells can be figured out. Further investigations will be reported on yeast cell samples deposited on paper filters after irradiation by soft X-rays. The results will be discussed by cross correlating the experimental evidence from Delayed Luminescence with those obtained by metabolic activity recording. Luminescence and Delayed Luminescence are strictly correlated with early insurgence of morphological alterations of normal or pathological nature in cells and tissues; a novel technique for morphological analysis has been developed by means of Focused Ion Beam machines. A straightforward approach to morphology at the nanoscale both of membranes and cellular inner structures is then made possible. The final aim is an experimental set up for an early and reliable detection technique for neoplastic cells and tissues sorting.

Cell probing by delayed luminescence

Delayed luminescence (D.L.) is a measure that provides important information on biological systems fields, structures and activities, by counting impinging and emitted photons. Many recent experimental works have shown the existence of a close connection, sometimes analytically expressed between the biological state of the system and D.L. parameters. Our investigations aim to show that D.L. is a workable analytical technique covering a large number of disciplinary fields, from agriculture to pollution control and from medical diagnostics to food quality control. The authors have conducted systematic research about D.L. from unicellular alga Acetabularia acetabulum to Saccharomyces cerevisiae yeast cultures and about more complex systems such as Soya seed (Glycine max, L.) and its dependence on sample preparation, history, intracellular signaling, metabolism and pollutant presence. We will discuss the most relevant results together with theoretical considerations on the basic interaction at work between biological systems and electromagnetic fields.