Synthesis of thromboxane B2 and prostaglandin F2 alpha by human platelets after contact with biomaterials used in vascular surgery.
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Biocompatible Materials↗
Biomedical subjects
E Cenni
Publications and source records attributed to E Cenni.
Effects of chromium extract on cytokine release by mononuclear cells.
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↗
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↗
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↗
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↗
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↗
[Assessment of various immunologic parameters in silicone implant carriers].
The Authors evaluated some immunological parameters in women carrying silicone gel-filled breast implants for over one year. Peripheral blood samples from 22 patients were examined in order to assess both the antigenic pattern of lymphocyte subpopulations by cytofluorimetric analysis, and the cell proliferation of PHA-stimulated lymphocytes by the uptake of tritiated thymidine. These tests were performed at the time of the sample withdrawal and after in vitro reexposure to silicone extract for 48-72h. Changes in lymphocyte subpopulations and functional response were observed when patients were divided into groups according to the type of surgery, i.e. breast augmentation or reconstruction, or to the degree of periprosthetic capsular contracture. These results suggest the possibility of an interaction between silicone and the immune system, which cannot be disregarded for the explanation of the silicone related complications.
Adult↗
[In vitro tissue factor production by human endothelial cells put in contact with polyethylene terephthalate with different texture].
The aim of this study is the evaluation of the in vitro tissue factor production by endothelial cells cultured in the presence of Woven or Knitted Dacron. The spectrophotometric evaluation of the protein content of the cultures and the both indirect assay and enzyme immune assay of tissue factor in cellular lysates were carried out after 72 hour contact between the cells and the materials under examination. The endothelial cell contact with Knitted Dacron did not determine variation in protein content, but it induced a significant increase in tissue factor production. The endothelial cell contact with Woven Dacron determined no significant variations neither in the protein content nor in the tissue factor concentration. It is concluded that Knitted Dacron, through the induction of tissue factor synthesis, can favour the extrinsic pathway of coagulation and therefore the production of thrombi. Woven Dacron, not inducing tissue factor formation, does not activate the extrinsic pathway of coagulation, as for the mechanism considered.
Blood Coagulation↗