Biomedical subjects

A Sabatucci

Publications and source records attributed to A Sabatucci.

4 recordsLinked to original sources

PubMed2005

Comparative analysis of deformation of two implant/abutment connection systems during implant insertion. An in vitro study.

AIM: The implant/abutment interface represents a crucial element to maintain the structural stability of the implant restoration and to prevent mechanical problems that can compromise the long-term success of the implant treatment. METHODS: In this study deformation of the external hexagonal and internal octagonal extension of 2 implants after applying different values of insertion torque has been tested. The implants were secured in a customized resin baseplate, with the implant neck exposed, then different values of insertion torque were applied by an electronic torque controller. RESULTS: Five internal octagonal implants were tested for 60 seconds to different torque magnitudes (12 Ncm, 21 Ncm, 27 Ncm, 36 Ncm, 42 Ncm). Two external hexagonal implants were tested for 60 seconds to a torque value of 27 Ncm and of 36 Ncm. CONCLUSIONS: After torquing tests, each implant was examined by a scanning electron microscope (SEM) medium and high magnification to evaluate the deformation of the 2 different antirotational systems. The SEM analysis of the internal octagonal and external hexagonal antirotational systems of the TBR implant showed a deformation proportional to the magnitude of the applied torque during implant insertion. The geometric deformation of the antirotational extension is capable of compromising its function after a torque magnitude of 36 Ncm or superior to this value. Moreover it was demonstrated a more evident alteration of the external hexagonal extension in comparison with the octagonal system after applying a torque value of 27 Ncm.

Composite Resins↗

PubMed2001

Comparison of the X-ray absorption properties of the binuclear active site of molluscan and arthropodan hemocyanins.

The structural characteristics of oxy- and deoxy-hemocyanins have been investigated using X-ray absorption spectroscopy both in the near-edge (XANES) and for the first shell contribution in the EXAFS region. Several arthropodan and molluscan hemocyanins have been studied in order to trace the inter- and intra-phyla differences. The XANES spectra of oxy-hemocyanins of the different species are remarkably similar, consistent with a very strongly conserved co-ordination geometry of the copper active site. In contrast, small but significant differences are observed between the deoxy-forms of arthropodan and molluscan proteins. In particular, the XANES spectra of deoxy-arthropodan hemocyanins (with the exception of L. polyphemus Hc) show a more intense edge feature at approximately 8983 eV. This difference is tentatively assigned to a more planar geometry of the copper-ligands system in the arthropodan rather than in the molluscan proteins. The first shell analysis of the EXAFS modulation is consistent with the presence of n=3Nepsilon(2) imidazole nitrogens at an average distance of 1.92 +/- 0.03 A from copper in all the deoxy-hemocyanins investigated. Binding of dioxygen results for all hemocyanins in the increase of the number of first shell back-scattering atoms to n=5 with average distances of 1.93 A. Alternatively, by separating the contribution of Nepsilon(2) imidazole nitrogens and of peroxide O-atoms, n=3 ligands at 1.98 +/- 0.03 A and n=2 ligands at 1.87 +/- 0.03 A are found.

Animals↗

PubMed2000

Saccharose solid matrix embedded proteins: a new method for sample preparation for X-ray absorption spectroscopy.

In this study, solid samples of hemoglobin and hemocyanin have been prepared by embedding the proteins into a saccharose-based matrix. These materials have been developed specifically for specimens for X-ray absorption spectroscopy (XAS). The preservation of protein conformation and active site organization was tested, making comparisons between the solid and the corresponding liquid samples, using resonance Raman, infra red, fluorescence and XAS. The XAS spectra of irradiated solid and liquid samples were then compared, and the preservation of biological activity of the proteins during both preparation procedure and X-ray irradiation was assessed. In all cases, the measurements clearly demonstrate that protein solid samples are both structurally and functionally quite well preserved, much better than those in the liquid state. The saccharose matrix provides an excellent protection against X-ray damages, allowing for longer exposure to the X-ray beam. Moreover, the demonstrated long-term stability of samples permits their preparation and storage in optimal conditions, allowing for the repetition of data collection with the same sample in several experimental sessions. The very high protein concentration that can be reached results in a significantly better signal-to-noise ratio, particularly useful for high molecular weight proteins with a low metal-to-protein ratio. On the bases of the above-mentioned results, we propose the new method as a standard procedure for the preparation of biological samples to be used for XAS spectroscopy.

Animals↗

PubMed1989

[Research on accidents in a tire-producing plant].

In the autumn of 1987 the U.S.L. health service (prevention, hygiene and occupational safety section) began a study about the accidents in a firm manufacturing tyres, placed in its own area. The retrospective enquiry starts from the analysis of typology, diffusion and seriousness of occupational accidents. The firm's accident register has been analyzed and integrated with other necessary information provided by the firm, by I.N.A.I.L. and by the air force metereological service. The study has been carried out on data concerning the following years: 1984-1985-1986. The accidents considered, implied absence from work and were divided as follows: for absence up till 3 days (in franchise), and more than 3 days (indemnified), applying the average value calculated on one year of the three analyzed. Every accident has been analyzed per year, month, day, hour of event. According to the classes: circumstances, kind of lesion, site of lesion, period of absence from work. The indices of: frequency, seriousness, incidence, mean duration have been calculated. The average monthly values of temperature: max and min. of the area and to the average monthly amount of processed elastomer (rate of production). The statistics we obtained, justified the study and showed the operative solution. The aspect of sanitary education and the general psychological aspect regarding the accident have been considered. Moreover the general operative solutions for the firm and specific ones for every department and for every position have been shown and faced up to. In this way, according to the risks that have emerged from the enquiries on previous accidents and thanks to direct inspection. it was possible to prevent accidents.

Accidents, Occupational↗