An expirical formula, continuous in field parameters and depth for 60 Co gamma radiation.
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Cobalt Isotopes↗
Biomedical subjects
M Benassi
Publications and source records attributed to M Benassi.
A new fractionation technique of total abdominal irradiation in ovarian cancer.
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Abdomen↗
Electromagnetic interference by GSM cellular phones and UHF radios with intensive-care and operating-room ventilators.
The aim of this study was to evaluate the risks deriving from the interference by radio handsets (GSM cellular phones and UHF radios) with intensive-care and operating-room ventilators. Tests were conducted in three hospitals in Rome on 22 lung ventilators in accordance with the recommended practice ANSI C63.18-1997. When electromagnetic interference (EMI) effects occurred, the authors determined maximum interference distances. They also evaluated the distances at which the use of a given handset would result in a 5% and a 95% probability of interference. The degree of risk posed by each observed event was estimated, and safe distances are suggested. EMI events of varying degrees and natures were observed even with transmitters placed at a considerable distance. All observed effects were temporary. Only three ventilators of a certain model stopped working altogether and had to be reset.
Electromagnetic Fields↗
Metabolic evaluation of sexual dimorphism. V. Action of testosterone on the phosphofructokinase of mice submaxillary gland cells in vitro.
1) The kinetics of phosphofructokinase and growth rate of submaxillary gland cells of C3H mice of both sexes in presence and in absence of testosterone have been studied. 2) Both enzymes show sigmoidal kinetics, with Hill's coefficient higher for the females. 3) The maximal activity is remarkably more elevated for the males. 4) The testosterone modifies the growth rate and the kinetic properties of the phosphofructokinase and these modifications depend on the sex.
Animals↗
Interaction of cytotoxic agents: a rule-based system for computer-assisted cell survival analysis.
The actual effectiveness of environmental noxious agents or anticancer drugs can be fully determined only by knowing if the effects (in the present case, the cytotoxic effects) induced by a given agent are enhanced by exposure to another (or other) agent(s). Given a certain combination of agents, it is possible to distinguish three types of interaction: (a) zero interaction or additivity; (b) positive interaction or synergism; and (c) negative interaction or antagonism. In this work, the methodological problems involved in evaluating the type and level of interaction between biologically active agents are discussed and an "intelligent" approach to the problem is proposed. In particular, a prototype of a computer-assisted rule based system, named CISA (Cytotoxic Interaction and Survival Analysis), designed in a KES environment (Knowledge Engineering System) and implemented on a personal computer, is described. By constructing isoboles based on experimental cell survival data and taking into account the relative confidence intervals, the system can indicate the appropriate combinations of dosages to be tested and finally determine the type and level of interaction. The system, which represents an attempt to administer "intelligently" the experimental data, is therefore able to identify the best strategy of analysis, to carry out the data processing and to offer suggestions to the investigator about the usefulness of the data and the planning of further experiments.
Animals↗
Cytotoxic effect of the association of BCNU with rhein or lonidamine on a human glioma cell line.
The effect of association of 1,3-bis-(2-chloroethyl)-l-nitrosourea (BCNU)- Rhein (RH) and BCNU-Lonidamine (LND) on the clonogenic activity of human glioma cells was evaluated. Both RH and LND modulate the lethal effect of BCNU regardless of the schedule of treatment. The analysis of the interactions, performed with the isbolar method according to Berembaum, demonstrates an additivity of the effects. The possible mechanisms as well as the implications for the design of brain tumor schedule treatment are discussed.
Anthraquinones↗
A simulation model for tumor growth controlled by therapeutic agents.
Results obtained in a controlled tumor growth depend on the experimental model used, the agent employed (drugs, ionizing radiations, heat), aw well as the administration scheduling and the host environment. Empirical search and treatment optimization are related to a discrete number of agent combinations and fractioning, and system parameters and dependencies are strictly connected to biological assumptions. A simplified model for the evaluation of the rate of change of tumor volume at the time of cytotoxic agent administration is proposed here, as well as a computer program to perform the simulation of tumor growth controlled by therapeutic agents.
Animals↗
Growth inhibition by rhein and lonidamine of human glioma cells in vitro.
The effect of Rhein (RH) and Lonidamine (LND) on the clonogenic activity of cultured human glioma cells has been evaluated. Both these drugs decrease the survival fraction, but their effect is strictly related to the duration of exposure. A brief exposure, i.e. 4 hours, even at the highest drug concentrations does not induce any significant decrease in the survival which, on the contrary, is strongly affected by 24 and 48 hours of exposure. The reason for this behaviour lies in the mechanism of action of these drugs which do not interfere with replicative processes, but selectively affect the energy metabolism of the neoplastic cell. The validity of currently employed screening tests to evaluate the antitumoral activity of non anti-mitotic drugs is also discussed.
Anthraquinones↗
Stereotactic irradiation therapy. Physical and dosimetric problems.
In stereotactic irradiation by external beams there are many problems involved with dosimetry of small fields, three-dimensional representation of dose distribution, radiobiological involvement of tissue response to total dose and fractionation. Dosimetric problems arise by critical dimension of dosimetric chambers and by difficulties of films calibration. The amount of data required for a correct three-dimensional simulation of isodose curves, tumor and anatomical structures require a very speed computer system, sophisticated computer graphic techniques and calculation algorithm. By use the linear quadratic model of cell survival, maps of combined dose and biological effect (isoeffect curves) are also obtained.
Brain Neoplasms↗
In vitro and in vivo potentiation by lonidamine of the antitumor effect of adriamycin.
Lonidamine (LND), a powerful antispermatogenic compound, has been shown to impair differentially the energy metabolism of normal and neoplastic cells and to increase significantly the survival of animal bearing experimental tumors. Clinical trials are presently ongoing and preliminary favourable results have been obtained with LND as a single agent or associated with other antineoplastic drugs. In this work the effect of the combination LND plus ADM was investigated on in vitro and in vivo tumors. The in vitro effect was analysed by the colony forming technique and the in vivo antitumor activity was assessed by means of local control parameters, increase in host lifespan and weight reduction of metastasing target organs (liver, kidney, ovary). The results obtained indicate that LND is poorly effective when used alone, while a very high cytotoxicity is observed when it is combined with ADM. Exposure of cells to different time-sequences and schedules of both drugs elicits a different response. In particular a synergistic effect is obtained when ADM precedes LND. These results have been preliminarily confirmed by in vivo studies.
Animals↗
A dielectric relaxation study on the effects of the antitumor drugs Lonidamine and Rhein on the membrane electrical properties of Ehrlich ascites tumor cells.
The effects of the anti-tumor drugs lonidamine and rhein on the plasma membrane electrical properties of Ehrlich ascites tumor cells were investigated and compared. Dielectric relaxation measurements in the radiowave frequency range (10(4) to 10(8) Hz) as well as at higher frequencies (10(4) to 10(9) Hz) were performed and the data elaborated using a "single-shell" fitting procedure. The results obtained in both frequency ranges indicate that membrane conductivity and membrane permittivity are altered by 200 microM Lonidamine while 150 microM rhein induces only very slight variations in these two plasma membrane parameters. The usefulness of the dielectric relaxation technique described here in evaluating antitumor drugs and improving clinical protocols is discussed.
Animals↗
A treatment planning system for stereotactic radiotherapy.
Stereotactic radiotherapy to treat neoplastic lesions or artero-venus malformations in the brain may be accomplished with a linear accelerator by performing several non-coplanar arcs of irradiation with a highly collimated beam focused on a fixed point. This paper introduces a system to perform treatment planning. It is based on a Personal Computer and allows the acquisition, reconstruction and visualization of the target volume, within the brain, from CT (Computerized Tomography) or MR (Magnetic Resonance) images, and then it permits calculation and visualization of a 3-D (three-dimensional) dose distribution due to small photon beams. The performances of the system and its use in a practical case are described.
Brain Neoplasms↗