Biomedical subjects

I Ortalli

Publications and source records attributed to I Ortalli.

8 recordsLinked to original sources

PubMed2001

Acetylphenylhydrazine induced haemoglobin oxidation in erythrocytes studied by Mössbauer spectroscopy.

The oxidative action of acetylphenylhydrazine (APH) on red blood cells obtained from healthy donors and from patients with breast cancer has been investigated by Mössbauer spectroscopy. Whole blood was incubated with APH for different time periods and the Mössbauer spectra of the packed red cells were recorded and compared. The evolution with time of the oxidation products has been followed. The largest difference in red cells analysis between healthy persons and patients was found after about 50 min of treatment where Mössbauer spectra of patient samples show a much broader spectral pattern due to an advanced haemoglobin oxidation.

Breast Neoplasms↗

PubMed1998

Study of dental materials by laser beam scanning.

Several properties of dental materials are characterized by dimensional variation induced by different parameters. In this work a non-contact method used for measurement of linear dimensional variation is shown. The accuracy is +/- 1 micron for sample length ranging from 1 to 70 mm.

Chemical Phenomena↗

PubMed1998

[The effects of hematin and Mössbauer gamma radiation in cellular inactivation].

In the present work we report the results of an investigation on cultures of bone marrow mononuclear cells collected from normal donors and patients with chronic myelogenous leukaemia and cultures of the human osteosarcoma cell line "MG-63" and the human osteoblastic cell line "HOBIT". We have examined the combined effects of hematin and 14.4 KeV gamma-radiation from a Mössbauer source. Growth stimulation has been observed when hematin is added to normal cultures, while growth inhibition is observed when hematin is added to tumor cultures. Different degrees of growth inhibition were observed in both cultures when hematin alone and hematin plus gamma-rays were administered to the cultures. No significant effect could be attributed to irradiation alone, while hematin plus irradiations show a large inhibition that expected for pure additive effects.

Bone Marrow Cells↗

PubMed1997

Polymerization shrinkage of microfilled composites determined by laser beam scanning.

An He-Ne scanning laser beam was used to measure for the first time the linear shrinkage of light-cured microfilled composites. A low-power beam, which has a wavelength (632.8 nm) different from the polymerization wavelength (approximately 450 nm), was used. In these conditions no shrinkage is induced by the laser light. This method of measurement makes it possible to analyse small samples with a very low error (1.1 microns). Five different materials were tested using 10-20 mg specimens, and the shrinkage process was examined in detail over 2 days. All these materials showed shrinkage of more than 50% of their original length after 1 min of irradiation and approximately 99% of the total shrinkage occurred 4 h after irradiation.

Acrylic Resins↗

PubMed1995

Porosity in composite resins.

Porosity in the pastes of composite resins before and after polymerization has been measured. The influence of the diameter of the extrusion orifices and the spatulation of the chemically-activated pastes has been evaluated. Considering that thin layers of these materials are transparent, the investigation has been carried out mainly by analysis of approximately 300 microns or lower thickness layers, that are still transparent under the microscope. Generally, there was a significant dependence of the porosity on the orifice diameter. However, this rule showed some exceptions. As far as the chemically-activated pastes were concerned, in all examined cases the number of small size (10-40 microns) porosities increased after spatulation.

Biocompatible Materials↗

PubMed1992

Dimensional stability of silicone-based impression materials.

This study attempts to demonstrate that the polymerization reaction is not the only factor that affects the shrinkage of silicone-based impression materials because evaporation of the constituents also contributes to the shrinkage. These factors can be evaluated by the study of time-dependent dimensional changes. This is shown both by chemical kinetics and by experimental testing of condensation and addition polymerizing impression materials with different viscosities. Comparison of the different materials shows that the two contributions, polymerization shrinkage, and evaporation shrinkage, can be assessed separately by analysis of the time-dependent shrinkage diagrams. The instability due to the polymerization reaction is complete after a few hours, but the contribution of the constituent evaporation, if present, can have a significant long-term role.

Dental Impression Materials↗

PubMedDate not supplied

Inactivation of bone marrow cultures and K562 leukaemic cell line by Mössbauer effect.

Bone marrow cells collected from normal donors and from patients with chronic myelogenous leukemia (CML) and cultures of the K562 leukaemic cell line, were investigated after treatment with hematin and low-energy gamma rays from a 57Co Mössbauer source. Different degrees of growth inhibition were observed for bone marrow cultures and for the leukaemic cell line K562. Exposure to light irradiation during sample treatments was also investigated. The results seem promising and it is author's belief that cell inactivation by Mössbauer effect could have future applications in the field of tumor pathology as an alternative to or in the support of conventional radiotherapy.

Bone Marrow Cells↗

PubMedDate not supplied

The possible role of hematin and Mössbauer effect in the inhibition of osteosarcoma cell proliferation.

Hematin, like many hematoporphyrines and porphyrin derivatives, shows a higher affinity and preferential localization for tumor cells. These properties are particularly interesting in view of their possible applications in tumor treatment. The aim of the present work was to test the capability of porphyrines and resonant low energy gamma rays to produce some kind of selective inhibition of tumor cell proliferation. We investigated the role of hematin to potentiate the killing capability of 14.4 keV resonant gamma rays from a 57Co Mössbauer source. Human osteosarcoma cell cultures "MG-63" were incubated in the presence or absence of hematin (10(-4) to 10(-5) M) for 24 hours. They were successively irradiated for 4 hours with 14.4 keV gamma rays from a 3.7 GBq 57Co source. The combined effects of hematin and resonant gamma radiation were then examined and tested statistically for significance. Different degrees of growth inhibition were observed when hematin alone, radiation alone, and hematin plus gamma rays were administered to the cultures. Hematin, at the concentrations of 10(-4) M is capable of inhibiting tumor cells growth. While no significant effect is attributable to irradiation alone, hematin plus irradiation show a larger inhibition than that expected for purely additive effects.

Cell Division↗