We have evaluated the effects of chromium extract on the release by peripheral blood mononuclear cells (PBMCs) of cytokines favouring bone resorption. Furthermore, we have evaluated whether the chromium effects could be correlated with the activation and proliferation of PBMCs. Cell cultures were maintained in serum-free medium (AIM-V), in order to avoid the interference of exogenous growth factors. Increasing concentrations of chromium extract, ranging between 3 and 100%, were added to culture medium. Cytokine release (IL-1beta, TNFalpha, IL-6, GM-CSF and IFNgamma) was assessed on both PBMCs cultured with AIM-V only (unstimulated PBMC) and PBMCs cultured with AIM-V plus phytohaemagglutinina (PHA-stimulated PBMC). The activation and proliferation of PBMCs were evaluated by assessing DNA synthesis and soluble IL-2 receptor release, in order to determine whether an IL-2-dependent immune response can be induced by chromium. Our results show that in unstimulated PBMCs chromium ions slightly increased the release of pro-inflammatory cytokines, such as TNFalpha and IL-6, even though the increase is not significant. On the contrary, the different concentrations of chromium extract significantly inhibited the response to PHA stimulation, as shown by the decrease in IL-6 and sIL-2r release, and by the influence on cell viability and DNA synthesis. Both these effects are undesirable and support hypotheses on the biological effects of chromium. The continuous release of chromium from the implant could induce in PBMCs the release of bone-resorbing cytokines, which in the long term could be responsible for irreversible tissue damage. Moreover, chromium seems to inhibit the IL-2-dependent response of PBMCs, so that they are not able to trigger an efficient cell-mediated immune response.

Bone Resorption↗

PubMedDate not supplied

Adhesive protein expression on human endothelial cells after in vitro contact with woven Dacron.

In this research adhesive proteins are studied in order to evaluate the interference of woven Dacron in the endothelialization process and in the ability of endothelial cells to bind circulating leucocytes. Endothelial cells from human umbilical vein (HUVEC) were put in contact with woven Dacron for 24 h. PECAM-1, ELAM-1, ICAM-1 and VCAM-1 expression was then evaluated by flow cytometry, using indirect immunofluorescence reaction with monoclonal antibodies. The study of adhesive proteins was completed with the quantitative determination of surface antigens expressed as the antibody binding capacity (ABC). Antigenic density was calculated by the DAKO QFIT calibration system for indirect immunofluorescence. After contact with woven Dacron no significant change was observed in the percentage of positive cells or in the fluorescence intensity of the adhesins. No significant variation was also noted by calculating the surface antigen density by means of calibration fluorospheres. It can be concluded that the material examined does not significantly affect leucocyte adhesion to the endothelium.

Biocompatible Materials↗

PubMedDate not supplied

The effects of metal corrosion debris on immune system cells.

Authors evaluated the correlation between immune system and metal ions release in blood of 17 subjects with Cr/Co/Ni joint prostheses. For the purpose Chromium (Cr), Cobalt (Co) and Nickel (Ni) serum levels were measured and, at the same time some immunological parameters (Leukocytes, Lymphocytes and Lymphocytes T, B and Natural Killer cells sub-populations) were evaluated. The results showed a significant decrease of Leukocytes, Lymphocytes and of T Lymphocytes sub-populations. At the same time it was demonstrated a significant increase of Chromium, Cobalt and Nickel levels in patients with joint prostheses as compared to control population (23 patients). In conclusion, ions release from metallic surface of the prostheses is correlated with a depression of immune system. This correlation could depend on a toxic action on immune system caused by the products released by the implant. It could also depend on a lymphocytes compartimentalization in periprosthetic tissues as a consequence of a cell-mediated hypersensitivity reaction towards implants corrosion products.

Adult↗

PubMedDate not supplied

Evaluation of cytokines regulating bone turnover in the serum of post-menopausal and senile women.

The authors evaluated the Insulin-like Growth Factor-1 (IGF-1) stimulating the formation of bone tissue, and interferon gamma (IFN gamma), inhibiting bone resorption, in the serum of women, 13 of fertile age, 34 of post-menopausal age, and 14 of senile age. Values for IGF-1 in the serum were considerably low in patients of post-menopausal and senile age, and presented highly significant differences with values for subjects of fertile age. The values for IFN gamma did not present significant differences between different age groups. It may be assumed that post-menopause and during senile age physiological osteopenia may be favored by a decrease in the secretion of IGF-1.

Adult↗

PubMedDate not supplied

Quantitative evaluation by image analysis of platelet morphological modifications after contact with polyvinylacetate.

BACKGROUND: In order to investigate platelet activation after contact with artificial materials, which is an important aspect of biocompatibility especially for the blood-contacting devices, platelet morphological modifications and spread area were evaluated by light microscopy and image analysis after contact with glow discharge-treated polybutylene terephthalate coated with a polymer for platelet concentrate filtration. METHODS: A hydrophilic polymer made of partially hydrolyzed polyvinyl-acetate containing polyethylene oxide/poly-propylene oxide copolymer block as lateral chains (PVA) (Biofil S.r.l., Cavezzo, Modena, Italy) was evaluated. After contact with PVA, platelets were allowed to settle on a siliconized slide and then fixed and stained. The specimens were analyzed by image analysis. The percentages of spreading, round and dendritic shapes, as well as the presence of aggregates, were evaluated, and the mean area of the spread platelets was measured. RESULTS: PVA induced significant variations neither in the percentages of shape change distribution, nor of the mean spread area. However it determined a statistically significant reduction in platelets with the area from 60 to 70 mu 2. Such minimal variations agree with the results we obtained in the past, namely a non significant platelet adhesion induced by the same material. CONCLUSIONS: The method confirms the results of platelet adhesion and release reaction (the study of release reaction needs more refined but more expensive methods). However, the study of morphological modifications by image analysis is not suitable for testing materials that induce massive platelet adhesion, because the number of the residual platelets could be too low for the microscopic evaluation.

Analysis of Variance↗

PubMedDate not supplied

[Dental implantations of ceramics-coated metals].

Recent studies and personal experience of the Authors in the field of dental implants have encountered the same fundamental problem which arises with orthopedic prosthesis procedures. The basic problem is that of adhesion between the bone tissue and the metal implant. Chrome-cobalt alloy, Tantalum and Titanium are the metals of most recent use. The Authors therefore proceeded to investigate the behaviour of alveolar bone tissue in the proximity of artificial teeth made of alloy (platinum-gold) covered with ceramic, as used in prosthetic dentistry. The experiment was carried out in a dog and a man. In the dog, two of its mandibular teeth were substituted with the same ceramic-gold implants: the first, a replica of natural tooth, was placed in the socket and held in place by metal splint and mandibular circumferential wirings. The other implant, without a replicated crown, was left free, within the alveolus, without contacting the near or opposing teeth. A solid smooth surfaced alumina device, shaped like a small cylinder, was implanted in the upper femoral epiphysis of the same animal.

Alveolar Process↗

PubMedDate not supplied

Cellular reactions in hip prosthesis loosening.

Based on the results obtained in histological examinations carried out on periprosthetic tissues in a large series of cases of prosthetic hip joint explants, the authors analyze the cellular events that may occur in loosening phenomena as compared to what occurs in the paraphysiological repair process that is observed in the stable prosthesis. Like other authors, they believe that the principal role in the mechanism of loosening is played by macrophages which are recalled in a large number, at times together with multinucleate giant cells, at the bone-implant interface, after micromovements of the prosthesis and the formation of wear particles have occurred. The macrophages would be capable of favoring resorption of the periprosthetic bone tissue, producing areas of osteolysis in which the transmission of the mechanical stress of loading is modified. The ensuing prosthetic instability increases wear phenomena, causes a greater amount of osteolysis, and, in a vicious cycle, loss of the relationship between bone and implant, and, thus, prosthetic loosening. Finally, the authors report a hypothesis on the pathogenesis of the phenomenon, based on which non-physiological stress, associated with wear and eventually infection, leads to loosening.

Bone Cements↗

PubMedDate not supplied

Considerations on ceramic prosthesis explants.

The authors report data obtained for 11 cases of explants of prostheses having ceramic joint surfaces. The wear phenomena observed in 9 prostheses, including 1 case with breakage of the ceramic head, was moderate: 20-22,000 debris per mu 2. In 2 cases the wear was massive, with a concentration of debris in the peri-implant tissues 5-10 times greater (100,000-218,000 debris per mu 2). An explanation for the trigger mechanism of wear phenomena is proposed: the cases of massive wear are related to loosening of the acetabulum. A histological examination of the bone tissue surrounding a stem covered with alumina (Al2O3) carried out in three cases allowed us to observe an area of demineralization measuring approximately 500 mu of tissue in contact with the ceramic coating. The osteomalacia could be caused by the diffusion of alumina ions.

Bone Cements↗