Biomedical subjects

A Pizzoferrato

Publications and source records attributed to A Pizzoferrato.

At least 55 records · Page 3Linked to original sources

PubMed1997

[In vitro production of endothelin-1 and prostacyclin by cultured endothelial cells in the presence of polymers].

The aim of this study was to evaluate endothelin-1 and prostacyclin production by human endothelial cells cultured in the presence of polyethylene terephthalate and collagen-coated PET. Cell counting and the assay of endothelin-1 and 6-keto-prostaglandin F1 alpha, stable metabolite of prostacyclin, were carried out after 48 hour contact of the cells with the examined materials. Endothelial cell contact with uncoated PET caused a significant reduction in cell number, a significant increase in the production of endothelin-1 and a not significant increase in 6-keto-prostaglandin F1 alpha. The endothelial cell contact with collagen-coated PET caused a highly significant decrease in cell number and a not significant decrease in endothelin-1 and 6-keto-prostaglandin F1 alpha. It was concluded that PET causes both a decrease in cell number and a remarkable increase in endothelin-1. On the contrary, collagen-coated PET determines a decrease in cell number and a slight reduction of endothelin-1 and 6-keto-prostaglandin F1 alpha.

Cells, Cultured↗

PubMed1997

[Plasma protein adsorption on variously treated +polybutylene terephthalate].

BACKGROUND: The aim of the research was the evaluation of plasmatic protein adsorption on untreated polybutylene terephthalate, corona treated polybutylene terephthalate and polyvinylacetate coated corona treated polybutylene terephthalate. METHODS: Total proteins, albumin, immunoglobulins, fibrinogen, insulin and ostecalcin were determined on plasma after contact with these polymers. RESULTS: Unsignificant variations were observed for the assayed proteins. CONCLUSIONS: The conclusions are drawn that the tested materials do not adsorbe significantly the most important plasmatic proteins.

Adsorption↗

PubMed1996

Activation of the plasma coagulation system induced by some biomaterials.

The ability of some biomaterials to activate plasma coagulation system was examined in vitro. After contact of platelet-rich plasma with biomaterials, some markers of the thrombin formation, i.e., fragment 1 + 2 and fibrinopeptide A, and some inhibitors of the blood coagulation mechanism were tested. Fragment 1 + 2 and fibrinopeptide A were found to be increased by all of the materials, though to a different extent. In particular, fragment 1 + 2 and fibrinopeptide A were significantly increased upon contact with polybutylene terephthalate and with collagen coated polyethylene terephthalate, respectively. Also antithrombin III was shown to decrease following exposure to biomaterials, but statistical significance was found only for polyethylene terephthalate and polyvinylacetate. As a results of this wide range of variability in the parameters, it is advisable to explore the plasma coagulation system with a multiparametric approach in which thrombin formation and coagulation inhibitors are thoroughly investigated.

Antithrombin III↗

PubMed1996

Assessment of metal extract toxicity on human lymphocytes cultured in vitro.

In this study the toxic effects of chromium, nickel, and cobalt extracts on in vitro cultured lymphocytes were evaluated. Graphite furnace atomic absorption spectrometry was used to measure the ion concentration. After serial dilution of the extracts, the viability of lymphocytes at 24, 48, and 72 h was estimated by flow cytometry, including propidium iodide staining and light scatter property assessment, and by MTT reduction test. The results of the investigation allowed us to conclude that 1) standardization of the procedure for preparing extracts is fundamental to obtaining repeatability of results; 2) the toxicity of an extract cannot be evaluated with a single viability assay; a combination of functional and structural tests is required; 3) when methods based on enzymatic reactions are performed, e.g. MTT test, it is advisable to replace the extract containing metal ions with fresh medium in order to avoid any interference with viability testing; 4) the amount of Co and Ni in the extract is similar, but the Cr release is very poor; 5) the lower toxicity of Cr extract probably is due to the lower ion concentration; 6) the assessment of 50% cytotoxic concentration (TC50) allows quantification of materials toxicity and comparison of various metals; and 7) the determination of a noncytotoxic concentration, i.e., a concentration lower than TC10, is required for subsequent investigation of cell functions because such studies can be carried out only on viable cell population.

Cell Survival↗

PubMed1996

Cytokine production and adhesive protein expression by endothelial cells after contact with polyethylene terephthalate.

The authors have evaluated adhesive protein expression and cytokine production by human umbilical vein endothelial cells cultured in contact with polyethylene terephthalate (PET). ELAM-1, ICAM-1 and VCAM-1 expression was determined by flow cytometry; the concentration of interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6), granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) in the supernatant was determined by enzyme immunoassay. The contact with PET determined a significant increase in ELAM-1 expression and insignificant increase in cytokine production, demonstrating that PET had a limited capability to stimulate endothelial cells in a pro-inflammatory sense.

Cell Adhesion Molecules↗

PubMed1996

In vitro assessment of phagocytosis of bovine collagen by human monocytes/macrophages using a spectrophotometric method.

The use of a wound dressing with covering and haemostatic properties significantly improves wound healing. In this study, a lyophilized bovine collagen sponge used for the treatment of wounds and ulcerae has been tested in a cell culture system. Phagocytosis of collagen fragments by human blood monocytes/macrophages has been investigated. For the assessment of collagen ingestion by mononuclear phagocytes, a picrosirius dye specific for collagen molecules has been used. By adapting this histochemical technique to microplate cell culture system, replicate monocyte cultures are assayed. Collagen content is determined by evaluating spectrophotometrically at 540 nm the absorbance of a sirius red/picric acid solution. Using this simple and sensitive method, the phagocytosis of bovine collagen by LPS-stimulated monocytes/macrophages has been ascertained.

Analysis of Variance↗

PubMed1996

The relationship of dehydroepiandrosterone sulfate (DHEAS) to endocrine-metabolic parameters and functional status in the oldest-old. Results from an Italian study on healthy free-living over-ninety-year-olds.

Dehydroepiandrosterone sulfate (DHEAS), the major circulating adrenal hormone, has been suggested to have a role in many aging related diseases and perhaps in aging itself. Its precise biologic effects are still unknown, and data on healthy people over 90 yr of age are not available. We measured serum DHEAS levels in 75 healthy subjects aged 90-106 yr of both sexes and searched for correlations between DHEAS and several endocrine-metabolic parameters (serum thyroid hormones, GH-insulin-like-growth factor I (GH-IGF-I) axis, serum lipid profile, anthropometric indices of body composition) of the same subjects. The resulting data, normalized by logarithmic transformation (geometric mean at age 90-99, 551 ng/mL in men, 364 ng/mL in women; at age > 100 yr, 404 ng/mL in men, 521 ng/mL in women) resulted five-fold lower than DHEAS levels measured in a young control group (geometric mean at < 40 yr of age, 3110 ng/mL in men, 2824 ng/mL in women). In women over ninety yr, DHEAS was positively correlated with serum free triodothyronine (FT3) levels (r = 0.34, P = 0.05) and inversely with triglycerides (r = -0.45, P = 0.05). In men over 90 yr, DHEAS had positive correlations with body mass index (r = 0.41, P < 0.03) and waist-to-hip ratio (r = 0.47, P < 0.01) taken as indices of body's energy reserves (fat). To determine whether low serum DHEAS levels predict poor functional status in the very old, the Activity Daily Living (ADL) test was administered in all over-ninety subjects. Men with the highest functioning levels had the highest DHEAS levels (P < 0.03). Our data suggest that DHEAS levels may influence and/or be influenced by several endocrine and metabolic features of oldest-old people, depending on the sexual steroid milieu. DHEAS seems also to have a strong interrelation with functional activities. A favorable role for DHEAS in successful aging is proposed.

Activities of Daily Living↗

PubMed1996

Application of a combination of neutral red and amido black staining for rapid, reliable cytotoxicity testing of biomaterials.

Cell viability and growth for cytotoxicity evaluation of materials for prosthetic devices has been tested using various methods. The aim of this study was to extend the choice of reliable methods to quantify cytotoxicity of materials in vitro. By measuring both viability and growth of cells exposed to biomaterials in vitro, two different parameters are analysed and quantified upon reading of the absorbance of coloured solutions in a spectrophotometer. Neutral red uptake and amido black staining of cells have been used for cell viability and cell number measurement, respectively: they have been found to be well correlated with the number of surviving cells. These methods have been adjusted to a 96-well microplate cell culture system and re-evaluated as simple and reliable methods for the quantitative assessment of biomaterial effect on cells.

Amido Black↗

PubMed1995

Silicone breast implants: the role of immune system on capsular contracture formation.

We evaluated the role of the immune system in the pathogenesis of the periprosthetic capsular contracture, the most frequently occurring complication following the implant of silicone prostheses. Peripheral blood samples from 22 patients with silicone-gel-filled implants were examined. In all cases a capsule was felt by palpation, and it was classified according to the Baker scale. Ten patients (group 1) had a Baker 2 contracture, and 12 (group 2) had severe contracture rated 3 and 4. The cells positive to antigens CD3, CD4, CD8, HLA-DR, CD19, CD25, CD57, CD16, and CD14, and the cytotoxic activity of the lymphocytes on target cells K562 were assessed by cytofluorimetric analysis. At time 0 there were no statistically significant differences between patients and normal subjects, nor between the two groups. At 48 h, the group 2 patients had a number/mm3 of cells CD57 + significantly higher than both group 1 and control group (P < .05). In group 1 patients, the cytotoxic activity was similar to that of normal subjects, whereas in group 2 it was significantly increased, in respect to both the controls (P < .05) and group 1 (P < .001). In all groups, the contact of the lymphocytes with the silicone extract did not modify either the antigen expression or the lymphocyte functional activity. On the basis of these results we hypothesize the involvement of the immune system in the formation of the capsular contracture around the prosthesis.

Adult↗

PubMed1995

Assessment of viability and proliferation of in vivo silicone-primed lymphocytes after in vitro re-exposure to silicone.

The functional response of peripheral blood lymphocytes isolated from 22 patients with silicone gel-filled breast implants was assessed after in vitro re-exposure to silicone. Using cell culture test methods to quantify proliferation and viability and/or activation of lymphocyte microcultures, i.e., the uptake of tritiated thymidine (3H-TdR uptake test) and the reduction of formazan salts (MTT assay), interesting data were obtained. Peripheral blood lymphocytes purified from patients wearing silicone gel-filled breast implants react in vitro to silicone showing a statistically significant increase of both proliferation and viability, while healthy subjects do not respond on in vitro exposure to silicone. Differences resulted even more statistically significant when patients were divided into two groups depending on the type of surgery they underwent: patients with breast augmentation for aesthetic reasons seem to have an increased responsiveness in vitro to silicone compared to patients who experienced a reconstructive surgery of the breast. Although they are still preliminary, being referred to a limited population, these results suggest that the lymphocytes of patients with silicone gel-filled breast implants could be sensitized in vivo toward silicone; the re-exposure of these cells to silicone leads to a higher functional response which could be looked for by using quantitative in vitro test methods.

Adult↗

PubMed1995

Microhardness of bone at the interface with ceramic-coated metal implants.

We evaluated bone microhardness at the interface with hydroxyapatite-coated stainless-steel pins used in an external fracture fixation system. Pins were transversally inserted into the diaphyses of sheep tibiae and were loaded in for 6 weeks. Uncoated pins were implanted as controls. Microhardness analysis, based on the measure of the resistance of the bone to the penetration of a small diamond pyramid, yielded an accurate and reproducible measure of the mineralization degree and of the orientation of collagen fibers. Bone tissue close to the pin is less hard than bone tissue far from it. Moreover, the presence of hydroxyapatite coating on the pins did not significantly affect bone hardness; actually, the mean hardness at the interface with the pins was 56.9 Vickers degrees, whereas at the interface with the uncoated pins it was 62.2. It can be concluded that, 6 weeks postsurgery, the bone growing into the threadings of a loaded screwed implant reached maturity at a degree lower than that of the host bone in both uncoated and coated implants.

Animals↗

PubMed1995

Microstructural investigation of bone-cement interface.

We evaluated the microstructural characteristics of newly formed bone tissue at the interface with cement. The bone-cement interfaces of the femoral components of nine hip prostheses retrieved after loosening were investigated by means of X-ray diffraction on microareas and microhardness. The bone far from the interface of two stable prostheses was used as a control. The newly formed bone adjacent to cement in the loosened prostheses showed a maturity degree lower than that of bone adjacent to cement in stable prostheses. The lattice parameters of bone apatite did not show significant variations as compared to the reference values. Bone trabeculae at the interface with loosened prostheses often showed an osteoid lining characterized by a strongly demineralized lamellar and haversian structure. Radioopaque cement particles are sometimes found in the trabecular bone tissue around the prosthesis.

Apatites↗

PubMed1995

In vitro effects of bone cements on the cell cycle of osteoblast-like cells.

The effects of orthopaedic cements on the proliferation and cell cycle of in vitro cultured MG63 osteoblast-like cells were examined. Five different cements were mixed and extracted at different time intervals (15 and 60 min, 6, 24 and 48 h). Cell proliferation inhibition (CPI) was evaluated after 72 h culture as the toxicity parameter. As for the toxicity degree, the extracts were considered to have 'high toxicity' (CPI > or = 50%), 'medium toxicity' (50% > CPI > 25%), 'low toxicity' (CPI < or = 25%) and 'no toxicity' (CPI = 0). Cell cycle phases of MG63 cells were evaluated at 24, 48 and 72 h by flow cytometry; the DNA content was assessed using the propidium iodide uptake and the percentage of cells in the S phase was determined using 5'-bromodeoxyuridine uptake. According to our results, the toxicity is inversely correlated with the time interval between polymerization and extract preparation, and is different according to the cement type. For some cements the effects are still observed 48 h after polymerization. The damaging effect is not linked to a specific phase of the cell cycle, nor does it hamper the restarting of cell proliferation at 72 h.

Bone Cements↗

PubMed1995

In vitro biocompatibility of a polyurethane catheter after deposition of fluorinated film.

The in vitro biocompatibility of an experimental surface-treated polyurethane was compared with an untreated polyurethane already used for intravascular catheters. The experimental surface was coated with a fluorinated film using a glow discharge treatment. Neither of the catheters was cytotoxic for L929 murine fibroblasts, caused platelet adhesion or release reaction, or changed the mean platelet volume. The surface-treated polyurethane, however, caused a higher adhesion of Staphylococcus aureus than did the untreated one. Therefore, using in vitro testing, it has been ascertained that the examined material, though not being cytotoxic and not modifying platelet behaviour, could favour bacterial adherence.

Bacterial Adhesion↗

PubMed1995

Platelet and coagulation factor variations induced in vitro by polyethylene terephthalate (Dacron) coated with pyrolytic carbon.

The haemocompatibility of polyethylene terephthalate (Dacron) coated with pyrolytic carbon was examined in vitro, evaluating its capability of inducing adhesion and platelet activation, and of modifying the intrinsic coagulation pathway. Platelet adhesion was evaluated by counting platelets before and after in vitro contact of human plasma with the material under examination. Platelet activation was evaluated by determining platelet factor 4 (PF4) and thromboxane B2. Intrinsic coagulation pathway alterations were studied by determining activated partial thromboplastin time (APTT) and the activity of single factors. The results obtained show that pyrolytic carbon-coated Dacron induces platelet adhesion, reduction in platelet volume and lower increase in thromboxane production than that obtained after contact with uncoated Dacron. Pyrolytic carbon-coated Dacron does not induce PF4 release, contrary to uncoated Dacron induces a significant release. Moreover, pyrolytic carbon-coated Dacron, induces a significant extension of APTT by reducing the activity of intrinsic pathway factors, particularly factor XI.

Biocompatible Materials↗

PubMed1995

Adhesive protein expression on endothelial cells after contact in vitro with polyethylene terephthalate coated with pyrolytic carbon.

This research aims at evaluating the expression of some adhesive proteins on endothelial cell surface with polyethylene terephthalate coated with pyrolytic carbon (PET + PC). Twenty-two different cultures of human umbilical vein endothelial cells (HUVECs) were put in contact with PET + PC. Both HUVECs grown without the biomaterial and HUVECs incubated with endotoxin were used as control. After 24 h, platelet endothelial cell adhesion molecule-1 (PECAM-1), endothelial leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were evaluated on the cells by monoclonal antibodies and flow cytometry. In agreement with the literature, after 24 h the culture incubated with endotoxin determined a significant increase in the percentage of positive cells for ELAM-1, a significant increase in fluorescence intensity of ICAM-1, and a significant increase in the percentage of positive cells and fluorescence intensity for VCAM-1. After 24 h of culture with PET + PC, no significant variations in the antigens examined were observed. This demonstrates that such material does not activate in vitro the proteins involved in the adhesion between leucocytes and endothelium or in the adhesion between endothelial cells themselves.

Antigens, Differentiation, Myelomonocytic↗

PubMed1995

Seven surgical silicones retain Staphylococcus aureus differently in vitro.

In an in vitro study, we have quantitatively evaluated the capability of seven different types of silicone to retain a Staphylococcus aureus strain, isolated from a surgical wound. All the silicone specimens were taken from prostheses already used in plastic or ophthalmological surgery. Two polymers were used as controls: polystyrene, because of its known capability to favour in vitro bacterial recovery, and nylon, for its bacterial repellence. The results show that all silicones are suitable substrata for Staphylococcus aureus. However, there are some differences among silicone types. The amounts of bacteria retained from silicone oils are greater than or equal to those obtained from the positive control material.

Biocompatible Materials↗

PubMed1995

Disposable contact lenses and bacterial adhesion. In vitro comparison between ionic/high-water-content and non-ionic/low-water-content lenses.

An in vitro quantitative study of the adhesion of a Staphylococcus aureus strain to two types of disposable contact lenses has been carried out. The first type was an ionic/high-water-content (I-HWC) lens (42% Etafilcon A, 58% water) and the second was a non-ionic/low-water-content (Nl-LWC) lens (61.4% poly(2-hydroxyethyl methacrylate), 38.6% water). Adhesion to the two lens types was evaluated both in basic conditions and after treatment with lysozyme. The results showed that I-HWC lenses are more prone to Staphylococcus aureus adhesion than NI-LWC lenses, both untreated (+15.4%) and treated with lysozyme (+20.5%). Lysozyme increased bacterial adhesion by 30.5% on the lenses with lower water content, and by 36.3% on those with higher water content.

Bacterial Adhesion↗