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Biomedical subjects

A Pizzoferrato

Publications and source records attributed to A Pizzoferrato.

At least 73 records · Page 4Linked to original sources
PubMed1992

Microradiographic and histochemical evaluation of mineralization inhibition at the bone-alumina interface.

Microradiographic and histochemical tests were used to examine the behaviour of the bone tissue close to the alumina coating in cementless hip prostheses which were radiologically stable and explanted because of pain. The presence was detected of a decalcification stripe of the bone tissue with a thickness of about 300 microns, parallel to the prosthesis profile and in appearance not influenced by the roughness of the surface. This phenomenon was attributed to the presence of aluminium ions similarly to what happens in osteomalacic osteodystrophy in nephropathic dialysed patients. It was concluded that the phenomenon must be carefully considered because, in the long term, it could cause failure in the alumina coating.

Aluminum↗
PubMed1992

Metabolic changes in bone in old age.

The authors conducted a study on the effect of aging upon the factors which regulate calcium metabolism. Hormonal and biochemical tests were performed on samples from patients selected on the basis of sex, age, and other characteristics in order to determine the trend of these regulatory factors in middle and old age, with particular attention to osteoporosis in women. The authors propose several theories regarding the pathogenetic mechanisms of osteoporosis on the basis of this study as well as the literature.

Adult↗
PubMed1992

[In vitro and in vivo evaluation of the blood-biomaterial interaction].

The Authors, after a short description of the phenomena following the interaction between blood and biomaterials, take into consideration the different methods used in studying the in vitro, in vivo and ex vivo hemocompatibility, as well as the problems involved by each method and its contribution to the knowledge of hemocompatibility. The Authors report their experience on the in vitro study of the effects induced by some biomaterials on platelets and coagulation factors.

Animals↗
PubMed1992

In vitro methods to evaluate metal-cell interactions.

The aim of this study was to test different metals, widely employed in constructing prosthetic devices, by in vitro methods. Biological effects of such materials were analyzed through four different assays on human lymphocytes and granulocytes. The lymphocyte proliferation assay gave quantitative results, while the viability test showed the morphological appearance of the cells correlated well with previous results. NK cytotoxicity and granulocyte chemokinesis tests provided interesting data on leucocyte performance when challenged with metals. Therefore the present study adds new basic information on cell behaviour when metal products are present in the body, e.g. around devices implanted in human tissues.

Biocompatible Materials↗
PubMed1991

Structural properties and biocompatibility of polymers used in ophthalmology.

The chemico-physical and structural properties and biocompatibility of new polymers used for intraocular lens manufacture are studied. In particular, the vibrational infrared and Raman spectra of fluorinated polymethacrylates are presented and discussed in relation to those of polymethylmethacrylate (PMMA), in order to correlate their structure with their properties and biocompatibility. The thermal analysis points out that the polymers are more stable than polymethylmethacrylate and the biocompatibility tests show that they are as biocompatible as polymethylmethacrylate.

Animals↗
PubMed1991

Cellular events in the mechanisms of prosthesis loosening.

The functional restoration of a joint damaged by trauma or disease is obtained by prosthetic surgery. In particular the implantation of hip prostheses is regarded as routine in orthopedic surgery and thorough research has been developed in this field. The prosthetic replacement of the knee and even more so the ankle and elbow occurs less frequently in clinical practice and has been studied less intensively. The results of artifical hip replacement are generally good, both in terms of pain relief and the restoration of satisfactory joint function. Nevertheless, as time passes, a high rate of failures have been recorded due to prosthesis infections, fracture and wearing of the prosthetic components and prosthesis loosening by various causes. The use of ultra-filtered air and laminar flow in operating theatres and antibiotic prophylaxis have dramatically reduced the incidence of infections in total hip arthroplasty. Thanks to the setting up of new stem configurations and the use of superalloys that are highly resistant to fatigue failure, the fracture of the femoral component has been virtually eliminated as a complication of total hip arthroplasty replacements. Loosening is thus the most frequent complication in total hip replacement.

Bone Cements↗
PubMed1989

Comparative study of the thromboresistance of Dacron combined with various polyurethanes.

In vitro tests were carried out on Dacron samples differently knitted and on Dacron vascular prostheses coated with various urethanes. All the materials were put in contact with human platelet-rich plasma; the subsequent assay of three platelet released substances, i.e. beta-thromboglobulin, platelet factor 4 and thromboxane B2, as well as the quantification of platelet retention, were used to establish the degree of thrombogenicity of the material itself. In some cases Dacron-urethanes composites showed better thromboresistance than any other materials conventionally used in vascular surgery.

Biocompatible Materials↗
PubMed1988

Multilayered bead ceramic composite coating for hip prostheses: experimental studies and preliminary clinical results.

The clinical use of a new ceramic composite material made up of multilayered alumina beads and adhered to a ceramic surface with a high-temperature-melting bioglass is proposed. The result is a structure characterised by a 27% porosity and an average pore diameter of 400 microns. The actual structure of the parts as well as their interface interaction were determined by Raman laser. The mechanical resistance of the adherence of this coating for the ceramic substratum was good enough to resist the stress to which it was submitted when used for a new model of prosthetic acetabulum. Experiments with rabbits revealed the good biocompatibility of the composite. The osteoproductive activity of the tissue surrounding the implant led to the gradual filling of the porosity with trabecular structures. The preliminary results of the clinical experience which began in November 1985, confirm the good compatibility of the ceramic composite.

Aluminum Oxide↗
PubMed1988

Results of histological grading on 100 cases of hip prosthesis failure.

One hundred cases of hip prosthesis failure were classified on the basis of the different types of tissue reaction occurring around alloplastic material. The results revealed infectious phlogosis in 32% of the cases, phlogosis due to wear in 42%, phlogosis due to allergy in 1% and mixed phlogosis in 25%. The distribution of the type and degree of intensity of the phlogosis, in relation to the duration of the implant, is also highlighted. This new grading technique yields reproducible results.

Biocompatible Materials↗
PubMed1988

Structural modifications and biological compatibility of doped bio-active glasses.

The Raman laser and infrared spectra of doped bio-active glasses of the 45S5 type are presented and discussed. The spectroscopic results show that the doping agents cause the destruction of the basic glass structure and the consequent formation of SiO4(4-) units in the glass network. When the doped glasses have been immersed in a physiological solution (199 medium), a film of calcite forms on the glass surface and this modification is related to the type of doping agent used, decisive for close linking between metal supports and the glass. The presence of doping agents does not prevent the normal growth of the bone onto the surface of doped bioactive glasses. Histological tests show that tissue response to very fine powders of doped glasses increases up to 15 days more or less according to the structural modifications revealed by spectroscopic measurements.

Animals↗
PubMed1987

[Computerized management in the surveillance of nosocomial infections].

A personal computerised system was developed for the on-going assessment and monitoring of hospital infections. The system involves the computer processing of clinical analyses. It also selects and statistically processes the data from microbiological tests conducted on hospital patients and staff. The system makes it possible to monitor the microbiological situation of the hospital environment with particular reference to the air, surfaces, instruments and material. In this way it is possible to identify the outbreak of minor hospital epidemics and to monitor their evolution and spread.

Air Microbiology↗
PubMed1987

The effect of injection of powdered biomaterials on mouse peritoneal cell populations.

The authors suggest an experimental model for the assaying, before implantation, of the tissue reaction that wear particles from artificial joints can cause in the human body. Mice were intraperitoneally injected with biomaterial powders in suspension in saline. The materials used were chromium, chromium oxide, nickel, nickel oxide, aluminum, alumina, alumina-titania, cobalt, molybdenum, titanium, silver, zirconium oxide, iron oxide, and stainless steel. Peritoneal lavage was performed a week after injection. A thorough morphological and quantitative analysis of the cell suspension thus obtained was made both immediately after collection and after a 24 h culture.

Animals↗
PubMed1987

Evaluation of autologous cancellous bone grafting of mandibular discontinuity defects in dogs using a Dacron-urethane prosthesis.

Reconstruction of 2 cm discontinuity defects using autologous cancellous bone chips and a Dacron-urethane prosthesis was evaluated in four canine mandibles. Histologic studies were performed on specimens taken six and 12 months after bone grafting. All four grafts were completely incorporated, producing a reconstruction that conformed precisely to the desired shape. Remodeling resulted in a trabecular pattern similar to that of the normal mandible. The prosthesis was well tolerated and did not elicit an inflammatory response.

Animals↗
PubMed1986

Postoperative irradiation of fresh autogenic cancellous bone grafts.

Discontinuity defects were created in the mandibles of dogs and then reconstructed immediately with fresh autogenic cancellous bone grafts and Dacron-urethane prostheses. The grafts were irradiated to a total dose of 5000 rads after waiting intervals of between 3 and 12 weeks. Nonirradiated grafts served as controls. The grafts were evaluated clinically, radiographically, and histologically. There was complete incorporation of all grafts, regardless of the interval between surgery and radiotherapy. There were no soft-tissue complications. The controls were distinguishable from the irradiated grafts only by the presence of hematopoietic bone marrow. Fibrofatty marrow was observed in the irradiated grafts. Theoretical support for this technique is found in the biology of cancellous bone grafting and the pathology of radiation injury. In view of the difficulties associated with mandibular bone grafting in preoperatively irradiated patients, a new method of reconstructing selected cancer patients who require both mandibular resection and radiotherapy is suggested.

Animals↗
PubMed1985

[Control of nosocomial infections].

Different factors involved in nosocomial infection and high risk hospital departments are examined. Methods of surveillance of infection in patients, in staff, and monitoring of environment and equipment are settled. The results obtained in environment monitoring and in some kinds of surgical operation are reported. A policy of epidemiological surveillance is proposed.

Cross Infection↗
PubMed1985

Prosthetic replacement of large defects of the cervical trachea in dogs.

Surgical resection and replacement of a segment of the cervical trachea was performed in 8 mongrel dogs. The replacement was with a porous prosthesis made of Dacron cloth mesh stiffened with a heat-curing polyetherurethane. Ten tracheal rings were resected in each animal to create a complete circumferential defect of the trachea measuring 7 or 8 cm in length depending on the size of the dog. Animals were sacrificed periodically from 3 to 27 months post-reconstruction. The luminal surfaces of the reconstructed tracheae showed respiratory epithelium.

Animals↗