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Biomedical subjects

A M Gatti

Publications and source records attributed to A M Gatti.

17 recordsLinked to original sources
PubMed1991

Long-term behaviour of active glasses in sheep mandibular bone.

Granules of a glass (A) prepared according to Hench's formula and a new vitreous material for biological applications (AKRA 15) were used for repair of bone defects in the dental field. The behaviour of these materials implanted in holes drilled in sheep's mandibular bone was examined 4, 8, 12 month after implantation. Microradiographic analyses, optical and scanning electron microscopic observations, and X-ray microprobe evaluations were carried out using undecalcified, methacrylate-embedded sections of the jaw containing the granules. After one year the granules of A disappeared, but not important bone growth was observed also in the holes containing AKRA 15. SEM and microprobe showed: disappearance of Na and Si ions at different stages; increase of P and Ca up to 4 month and then decrease, but in different ways in the two glasses; unexpected appearance of K ions after 4 month only in AKRA 15.

Animals↗
PubMed1991

Short-term behaviour of two similar active glasses used as granules in the repair of bone defects.

The bioactivity of two similar vitreous materials used in the form of granules of 'critical' size was investigated in bone defects in jaws of two sheep. The granules consisted of Hench's Bioglass and another glass with the same chemical composition made in Italy. Two months after implantation, the sheep were killed and elemental analyses carried out on sections of the embedded jaws. The microanalyses for both the glasses showed a diffusion from the granules towards the surrounding tissue of silicon and sodium, and an inverse diffusion (from the surrounding tissue towards the granules) of calcium and phosphorus. The degradation for the Italian glass was slower than for the Bioglass. No significant osteoinduction was seen after that time at the interface of the glass granules or in the bone pocket.

Animals↗
PubMed1991

Calcification of chemically treated bovine pericardium.

One of the most important problems arising in cardiac bioprostheses made with bovine pericardium and, more generally, with biologically-derived tissues is tissue calcification. The present study assessed four chemical treatments on patches of bovine pericardium, intended to avoid or minimize calcification. Pericardium specimens were treated with: A) 0.5% glutaraldehyde; B) 0.5% glutaraldehyde + 4% formaldehyde; C) same as A, but with a further neutralization treatment; D) acylation of fresh bovine pericardium. Circular samples of 1 cm diameter were subcutaneously implanted in the abdominal region of three groups of six rats. The explants were retrieved after 2, 4 and 8 weeks. The calcium content and the histological results showed better behaviour for C and D samples than with the commonly used fixation methods (A and B). The lowest calcification was observed with treatment D, even though its morphological structures were somewhat modified with homogenation of collagen bundles. Among the glutaraldehyde-based treatments, treatment C appears to be the most promising because the pericardium shows slower calcium accumulation with a diffusive pattern.

Animals↗
PubMed1990

Behaviour of tricalcium phosphate and hydroxyapatite granules in sheep bone defects.

Granules of hydroxyapatite (HA) and tricalcium phosphate (TCP) were implanted in separate holes drilled in mandibular bone of sheep to check the bone growth and in vivo behaviour of the materials. The experiment was performed in three sheep, killed respectively at 4, 8, 12 month. Samples of bone with the materials were explanted, microradiographed and sectioned to evaluate the interface under optical and electron scanning electron microscope. The hole, left empty as a reference, showed no full repair; whereas 4 month after implantation the TCP granules induce total repair of the hole. HA granules crumbled and no new bone induction was seen even 12 month after implantation.

Animals↗
PubMed1990

Comparative analyses among interfaces of some ceramic materials and bone in sheep.

Aim of this work is the evaluation of "in situ" implants in an animal model to study the interfaces that some ceramic materials for dental bone defects develop with bone and to check which material is more osteoconductive. In a sheep's jaw, eight holes were drilled and filled with six ceramic materials in granular shape. Two bilateral holes were left empty as reference. The ceramic materials were: porous tricalcium phosphate (TCP), porous hydroxylapatite (HA) and four bioactive glasses. The glasses differ for doping agents that affect the velocity of biodegradation in the living body. Monthly radiographs were taken and the X-ray pictures analyzed by means of a Video Display Computer in order to quantify the optical density changes occurred in the holes. After 4 months implantation, the segments of the jaw containing the materials were fixed in paraformaldehyde, embedded in methylmethacrylate and sectioned. The results obtained under the microradiograph, the SEM and the X-ray microprobe showed a good bone repair only with TCP granules. A great degradation was seen in HA granules and particularly in glasses. The degradation modified the structure and the composition of the glass granules, but it was not followed by a consequent bone deposition.

Animals↗
PubMed1990

[Monocrystalline aluminum dental implants in animals: a study of the peri-implant tissue].

After the extraction of two molars in a dog's jaw, a single crystal alumina screw was implanted. Monthly radiographs were taken and analyzed by means of a video display computer (VDC) to obtain densitometric informations about the interface. After one year implantation, the bone segment containing the prosthesis was fixed in 4% paraformaldehyde, embedded in methacrylate and sectioned by a microtome saw. The results in light microscopy with ordinary and polarized light, in SEM and X-ray microanalysis, show the presence of a thick connective tissue layer interposed between the screw and the bone. The histological findings confirm the results obtained through the VDC analysis of the radiographic images.

Absorptiometry, Photon↗
PubMed1989

MACOP-B treatment for advanced stage diffuse large cell lymphoma: a multicenter Italian Study.

Seventy-one patients with advanced stage diffuse large cell lymphoma were treated with MACOP-B. Sixty-nine per cent of patients achieved a complete response (CR), 10% a partial remission, while 11% had no response and 10% died because of toxicity. The CR rate was adversely affected by immunoblastic type, poor performance status and bone marrow involvement. Two-year survival for all 71 patients was 55% and 2-year disease-free survival (DFS) for the 49 CRs was 73%. Relapses were lower (P less than 0.05) in patients achieving CR in 8 weeks or less (DFS 83% vs. 59%) and in patients without tumor bulk (DFS 87% vs. 54%). Overall toxicity was acceptable with mucositis proving to be the most frequent severe side-effect. However, treatment-related deaths were unacceptably high in patients over 59 years of age (30% vs. 7%). Thus for the elderly MACOP-B is potentially lethal and must be used cautiously. These preliminary results confirm the effectiveness of MACOP-B. The delay of response and/or the presence of tumor bulk may be important prognostic factors in identifying a subset of poor risk patients with a high incidence of relapse.

Adolescent↗
PubMed1989

[Therapeutic aspects of hairy cell leukemia].

This work considers the new advances in hairy cell leukemia therapy. During the last decades the only useful treatments were splenectomy, or, in case of failure or relapse, various chemotherapeutic approaches. Sometimes leukapheresis, radiotherapy, androgens, allogenic bone marrow transplantation, corticosteroids and lithium salts were used with few good results. Interferon and 2-deoxicoformycin recently introduced for the treatment of HCL have determined a dramatic change in the outlook of this disease, producing a high percentage of complete and partial remission.

Antineoplastic Agents↗
PubMed1987

UV-radiation aging test on composite materials for dental restorations.

Seven composite materials for dental restorations were examined in order to investigate their color stability. Five of these materials are available for anterior and two for posterior teeth. The change in color was achieved by an accelerated aging test with ultraviolet rays and evaluated, for each material, with the measurement of reflectance. Such measurement was obtained by means of a video display computer working as a computerized photometer. The results show two different types of behavior: some materials turn slightly to yellow, while others bleach. The test was completed with a scanning electron microscope morphologic examination of the surfaces.

Color↗
PubMed1987

The evaluation of the interface between bone and a bioceramic dental implant.

Methods for evaluating the interface between bone and an experimental dental implant have been analyzed. The material studied was a titanium implant coated with a mixture of alumina and titanium dioxide by means of a plasma-jet system with the dog as the animal model. The evaluations were made on two levels: (1) in vivo, by analyzing radiographs of the peri-implant zone with a video display computer (2) in vitro, after explantation, by analyzing vertical and horizontal sections of the sample with an optical and a scanning electron microscope, and by a video display computer analysis of the microradiographs of these sections.

Aluminum Oxide↗
PubMed1986

Cephalometry with a video display computer.

A new technique to develop cephalometric analyses for orthodontic problems is illustrated. A digital analyzer of images is employed in our laboratory, and this allows us to get the X-ray picture digitized and displayed on both a black and white and a colour TV screen. All the cephalometric points are selected by an operator who watches a coloured cross which can be moved on the colour TV screen by means of a keyboard. A suitable software was developed to calculate linear and angular measurements. The cephalometric coloured lines appear at the top of the X-ray image and the data are displayed on a monitor, from which a print-out is obtained. Such a technique has some advantages: the X-ray image can be processed before the cephalometric analysis to enhance details, thus making the analysis more accurate; the cephalometric lines can be seen on the X-ray image displayed on the colour TV screen and can be photographed or stored on floppy or rigid disc.

Cephalometry↗
PubMed1985

In vitro computerized evaluation of biological cardiac prosthesis calcification.

The late valvular bioprostheses failure is mainly related to leaflet calcification. This study reports a new approach to testing the biological prostheses calcification applying a computerized technique to x-ray picture. A bovine glutaraldehyde-fixed bioprostheses (BB) was implanted in two sheep in mitral position. The experimental procedure was performed on valves explanted six months after surgery. The BB x-ray pictures were tested by means of a video display computer (VDC) that can process radiographic, photographic or microscopic images and also evaluate the optical density of image quantifiable. The calcification zone assumes different values according to the calcification degree. The VDC can colour the BB x-ray images and display them on monitors (one black and white, one colour) with the colours strictly related to the grey levels of the image.

Animals↗