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Biomedical subjects

M Visentin

Publications and source records attributed to M Visentin.

At least 19 recordsLinked to original sources
PubMed2006

Determination of crystallinity and crystal structure of Hylamer polyethylene after in vivo wear.

Hylamer polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer components used in joint prostheses, if sterilized by gamma rays in the presence of oxygen, are easily affected by wear, which leads to osteolysis. The authors have analyzed the crystallinity of polyethylene liners removed from seven patients who had received Hylamer polyethylene implants sterilized by gamma rays in air and had suffered prosthetic loosening, using Raman spectroscopy coupled with partial least squares (PLS) analysis. The results have been compared to those of two controls who had received Hylamer polyethylene implants sterilized by gamma irradiation in a nitrogen atmosphere. The crystal structure of wear particles released into the tissues from the Hylamer liners sterilized by gamma rays in air is also studied. The materials undergoing two different types of sterilization methods show different crystallinity values (71.50 vs. 69.43), but the crystallinity do not change according to wear (worn and unworn liner region). Both monoclinic and orthorhombic phases are present in the liner, while in wear debris prevalently monoclinic crystals are found in both types of sterilized liners. Different crystallinity rates can explain different wear rates observed in vivo.

Aged↗
PubMed2006

A case report of fracture of ceramic head in total hip arthroplasty: histological and biochemical features of perimplant tissues.

The authors analyzed the case of a patient with a non-cemented hip prosthesis with a ceramic-ceramic coupling. As a consequence of trauma the head fractured. Although the patient could feel the joint grinding, there was no pain and he continued daily living activities for nearly six months, which led to marked wearing of the ceramic head. SEM analysis with microprobe showed 'planed' surfaces on the ceramic head, suggesting repeated movements between the fractured components. Inside the cone of the head, signs of TiAlV, which is an alloy of the prosthetic stem, could be seen. Periprosthetic tissues were packed with ceramic wear particles of sizes ranging between 0.2 and 10 microns, according to the harvest site. Metal and mixed particles were also found. IL1, IL6, IL8 and IL10 assays in the synovial liquid confirmed the inflammatory state and a modest induction of bone resorption, which was less than that observed in patients with loosened metal-polyethylene couplings. The humoral picture was compatible with the radiological aspect, which did not show marked signs of bone resorption. In revision surgery both ceramic components were replaced by a metal head and polyethylene liner. The clinical outcome after 12 months was very good.

Alloys↗
PubMed2005

Behavior of Hylamer polyethylene in hip arthroplasty: comparison of two gamma sterilization techniques.

Hylamer polyethylene was introduced in the 1990s as an alternative to conventional polyethylene. Its chemical and physical properties, and especially its high crystallinity, were claimed to improve resistance to wear. Initially Hylamer devices were sterilized by gamma radiation in air, then the technique was changed and gamma radiation was performed in the absence of oxygen. Clinical experience has shown the early loosening of some devices made from Hylamer. The aim of this study was to ascertain whether early wear and consequent osteolysis was linked to the sterilization method. We retrospectively compared 31 patients with hip prostheses with Hylamer liners sterilized by gamma radiation in air (group 1) with 30 patients with the same prosthesis, but sterilized in the absence of oxygen (group 2). The groups were similar for sex, age, disease, head diameter and material. Mean follow-up was 84 months and no clinical signs of failure were present. Radiographic measurement revealed that wear of group 1 was significantly greater than that of group 2 (0.23 mm/year vs 0.09 mm/year, p=0.001). Periacetabular and femoral osteolysis in group 1 was significantly greater than group 2. In conclusion, the method of sterilization might have influenced the outcome of Hylamer polyethylene liners.

Arthroplasty, Replacement, Hip↗
PubMed2005

Isolation and characterization of wear debris generated in patients wearing polyethylene Hylamer inserts, gamma irradiated in air.

Hylamer polyethylene was used in the early 1990s to make hip-joint components. Clinical experience has shown that these components, if sterilized by gamma rays in the presence of oxygen, are easily affected by wear, which then leads to osteolysis. The authors analyzed polyethylene wear particles in seven patients who had received Hylamer polyethylene implants sterilized by gamma rays in air and had suffered prosthetic loosening. The results were compared to those of six controls, who had received traditional polyethylene implants, sterilized by the same method. The frequency distribution of globular and fibrillar particles was similar in both groups (38.5% in Hylamer, 45.2% in controls). The globular particles in the Hylamer samples had a mean area of 0.12 microm2, which was significantly lesser than that of the controls (0.30 microm2). The width of fibrillar particles in the Hylamer samples was significantly lesser than that of the controls. Therefore, the two materials, despite undergoing the same type of sterilization, produced different types of wear, due to their different properties. In conclusion, the difference in the morphology of Hylamer polyethylene wear particles in comparison with PCA might have caused a more intensive biological response, early and massive osteolysis, and therefore, early loosening.

Aged↗
PubMed2002

Nitric oxide synthase in tissues around failed hip prostheses.

Nineteen patients who had undergone hip revision surgery for aseptic loosening of joint prostheses were studied. Tissue samples were harvested at the interface between bone and implant, either at the stem or at the cotyle level. Immunohistochemistry was performed on tissue sections to detect nitric oxide synthase (NOS), the enzyme which enables the synthesis of nitric oxide (NO), a molecule which can activate bone resorption. Quantitative analysis of the positive cells and correlation with the presence of particulate wear debris and radiological data were performed. The authors observed a trend towards a moderate increase in positive cells due to inducible NOS in tissues containing particulate wear debris, especially of a plastic material. This increase, however, did not achieve statistical significance. On the contrary, there was a statistical correlation between iNOS (inducible NOS) and the severity of osteolysis around the prosthetic implant. Pharmacological control of the biosynthesis of NO may be considered in the prevention or treatment of loosening.

Adult↗
PubMed2001

Knowledge and attitudes of Italian medical staff towards the approach and treatment of patients in pain.

This study is part of the project, "Towards a Pain-Free Hospital," which aims at improving the approach and treatment of the patient in pain. The objective of the study was to evaluate the knowledge and attitudes of doctors and nurses on the wards of a 1000-bed general hospital located in a rather densely-populated, industrialized area of Italy regarding the following topics: attention paid to pain, the use of analgesic drugs, and pain in children. In total, 669 nurses and 225 doctors completed a 16-item questionnaire evaluating knowledge and beliefs about pain. The overall percentage of correct answers was 61% (9.7/16). The score varied among the different wards and ranged from 48% (7.8/16) to 76% (12.3/16). Physicians scored 65% and nurses 59% (p < 0.001). The percentage of correct answers varied widely among the different items (from 30% to 96%). From these results, we conclude that there are still significant knowledge deficits and erroneous beliefs that may hamper treatment of the patient in pain. These results will help in conducting educational programs aimed at improving pain treatment in the different departments of the hospital.

Adult↗
PubMed2000

Sister chromatid exchanges and ion release in patients wearing fracture fixation devices.

The quantification of sister chromatid exchange (SCE) during mitosis is a useful index for evaluating genotoxic effects in subjects occupationally or incidentally exposed to potentially toxic substances. The authors investigated the hypothesis that ions released by corrosion from prosthetic components of fracture fixation devices are associated with change in SCE incidence. In the present study, ten patients with implants were examined, and fifteen subjects with no implants were used as controls. SCE and high frequency cell (HFC) numbers were evaluated in circulating lymphocytes. In addition, nickel (Ni) and chromium (Cr) ion values in the serum were measured because, after iron, these metals are major components of stainless steel. A significant increase in SCE numbers was observed in patients compared to the control population (4.9 +/- 1.3 vs. 3.5 +/- 1.4). Ni concentration was 1.71 +/- 1.49 ng/mL in patients and 0.72 +/- 0.52 ng/mL in control subjects; Cr concentration was, respectively, 1.01 +/- 0.77 ng/mL and 0.19 +/- 0. 27 ng/mL. The increase of serum Cr and Ni was statistically significant. No correlation was found between the increased Cr concentrations and SCE number while Cr ion levels were found to be significantly correlated to HFC. An inverse correlation between Ni level and SCE numbers was observed. Our findings suggest that Cr release by stainless steel implants could have a genotoxic effect; thus it would be useful to carefully monitor implanted subjects with regard to serum ion dosage, SCE analysis, and HFC evaluation. In any case, it would be appropriate to remove the implant when fracture fixation is reached.

Adolescent↗
PubMed2000

Cytokines and osteolysis around total hip prostheses.

The aim of this work is to assess the correlation between the osteolysis around the prosthesis and the presence of cytokines favouring inflammation in the tissues at the interface between loosened prosthesis and bone. In this study, twenty-nine patients that underwent revision surgery were examined. Bioptic samples were collected at the interface between bone and implant both at the stem and socket level. Semiquantitative immunohistochemistry was performed to detect interleukin 1 alpha, interleukin 1 beta, interleukin 6 and tumour necrosis factor, cytokines that directly cause bone resorption and indirectly induce synthesis of other bone resorbing cytokines. Wear particles were identified and quantified by light microscopy. Radiographic evidence for osteolysis was scored by the Engh and Bobyn score. In tissues collected at the interface, the percentage of cells positive to IL1, IL6 and particularly to TNF increased in relation to the tissues collected at the interface with stable components. The cells occurring in the new capsule do not secrete cytokines in quantities that can be related to severity of wear. Cemented prostheses showed higher incidence of severe osteolysis, and higher levels of cytokines. It can be concluded that TNF, and to a lesser extent IL1 and IL6, are positively related to the severity of osteolysis around the prosthesis and therefore a pharmacological treatment can be hypothesized with anti-inflammatory or anti-cytokine drugs in order to limit or to avoid prosthesis loosening.

Adult↗
PubMed2000

Osteochondrodystrophic lesions in chelated thalassemic patients: an histological analysis.

Some patients affected by thalassemia major and treated with an iron-chelating drug such as deferioxamine can suffer from severe osteochondrodystrophic lesions of the long bones. These lesions were radiologically and clinically evident in 2.8% of the patients we examined over the last 10 years. The aim of our research was to evaluate the morphology and morphometry of five tibial biopsy specimens taken from thalassemic patients with bone lesions and two bone biopsy specimens taken from thalassemic patients with no alteration of the long bones. All the bone samples showed a similar morphostructure. Abnormal chondrocytes, alteration of cartilage staining pattern, irregular columnar cartilage, and lacunae in the cartilaginous tissue were revealed histologically. Osteoid thickness was either normal or slightly increased. Some bone trabeculae had microfractures and some had cartilagineous oases. In five cases, iron deposition was detectable by Perls' Prussian Blue staining. It can be concluded that even in patients without radiographic signs of lesions, seriously damaged columnar cartilage, altered bone mineralization, and microfractures are common.

Adolescent↗
PubMed2000

Apoptosis in peri-implant tissue.

The authors examined 54 biopsies taken from the tissue surrounding loosened hip joint prostheses. In situ apoptotic cell identification was performed by the detection of single- and double-stranded DNA breaks that occurred in the early stages of apoptosis. Both types of breaks can be revealed by labeling the free 3'-OH termini with modified nucleotides (fluoresceine-dUTP) in an enzymatic reaction catalyzed by terminal deoxynucleotidyl transferase (TdT). Results were correlated with the presence of wear debris in the tissue and with the use of bone cement for prosthesis fixation. Apoptotic cells were present in a higher percentage in tissue sections where metal particles were present (24% apoptotic cells) if compared to areas where no wear (6%), or plastic wear (2.8%) or ceramic wear (1.5%) was observed. Apoptosis is neither related to bone cement, nor to the time it takes for the implant to fail. Cell death by apoptosis may be important in implants which release metal ions by corrosion or wear and may have been underestimated up to now, as it is a 'clean' way of cell death, leading to limited damage in the surrounding tissues.

Acetabulum↗
PubMed2000

Sister chromatid exchange in patients with joint prostheses.

The evaluation of sister chromatid exchanges (SCE) is used to establish the cytogenic damage in subjects exposed to toxic substances. The test is considered to be 1 of the most sensitive and accurate indicators of damage and responds to toxic chemicals at low doses. We evaluated the incidence of SCE in peripheral lymphocytes of patients with articular prostheses. Subjects with prostheses made of titanium-aluminium-vanadium alloys presented a significantly higher SCE number than the control population (6.3+/-2.3 vs 4.4+/-1.3; P = .0128), whereas subjects with prostheses made of chrome-cobalt alloy or mixed prostheses presented a higher SCE value than the controls but not significantly different. The presence of high-frequency cells was alarming only in 5 patients, 4 of whom had titanium alloy prostheses, whereas none belonged to the control group. The number of SCE was not affected by the presence of bone-cement used in prosthesis fixation or by the implant duration. The indication of possible cytogenic damage in patients with titanium alloy prostheses that emerged from this study should be considered carefully, even though the sample population was small.

Adult↗
PubMed2000

In vitro investigation of aluminum and fluoride release from compomers, conventional and resin-modified glass-ionomer cements: a standardized approach.

The amount of fluoride release from dental cements necessary for an anticariogenic effect is not established: moreover, the possible toxic effects due to high fluoride and aluminum release are not well known and the results are still controversial. The aim of our study was to evaluate fluoride (F) and aluminum (Al) release from dental cements using a 'standardized approach' according to the end-use of the materials, i.e. biocompatibility testing. Two polyacid-modified resin composites of recent application, commonly called compomers (Dyract and Dyract Cem), were compared with two conventional acid-based (Fuji I, Ketac-Cem) and two resin-modified (Vitremer, Vitrebond) glass-ionomer cements (GICs). All types of cement are used in dentistry and are commercially available. Extracts of the cements into minimum essential medium, after setting over a 1-h (group A) and 1-week (group B) period, were performed. The extraction conditions were rigorously standardized. Mean values +/- standard deviation of F- and Al-levels in such extracts were measured and were expressed as microg g(-1) (micrograms of ions per gram of cement). A great difference in the amount of ion release, both F and Al, was shown among the tested materials. The GICs, as well as Ketac-Cem, released more F and Al than the compomers. All of the materials released the greatest proportion of ions when the extraction was performed in the first hour after mixing (group A). Al- and F-values showed a highly significant positive correlation, independently from the curing time. We conclude that the biological assessment of dental cements can be performed only if a pre-evaluation of the leachables is obtained by applying a standardized protocol which allows a useful comparison between the different materials.

Aluminum↗
PubMed2000

[The predictive lidocaine test in treatment of neuropathic pain].

BACKGROUND: In daily practice, the intravenous lidocaine drip has been introduced as a predictive test for subsequent oral treatment with adjuvant drugs (anti-depressants, channel blockers and anti-convulsants). Our aim is the assessment of the correlation between the test response and the effectiveness of the consequent oral drug therapy. METHODS: 183 inpatients (central and peripheral neuropathic pain), treated between 1996-1997, were retrospectively checked. The trial was conducted as follows: a VAS reading > 5 was taken; a subsequent continuous i.v. lidocaine drip was given, at a dose of 4 mg/kg, in saline solution; a VAS reading was taken before (VAS 0), every 5 minutes, and at the end of the drip (VAS 1); the results of the drip were to be considered positive where pain relief was > or = 50%; irrespective of test results, all patients were given a different follow-up drug therapy; a VAS reading was taken one month after the drug therapy (VAS 2). RESULTS: Eighty-five patients (90%), responders to lidocaine, had a pain relief and 71 patients (85%), no responders to lidocaine, did not have improvement by taking oral drugs. CONCLUSIONS: In agreement with a other authors, we also noted that there was a statistically significant correlation between the results obtained and the therapy prescribed; the usefulness of a lidocaine drip as routine procedure to predict the therapeutic response of neuropathic pain to adjuvant analgesics is underlined.

Adult↗
PubMed1999

Wear debris and cytokine production in the interface membrane of loosened prostheses.

In this study, thirty-nine patients were examined. All of them suffered from hip joint prostheses loosening and underwent revision surgery. Bioptic samples were collected at the interface between bone and implant either at the stem or cotyle level. Immunohistochemistry was performed to detect IL-1alpha, IL-1beta, IL-6 and TNF, cytokines that directly cause bone resorption and indirectly induce synthesis of other bone resorbing cytokines. Quantitative analysis of the positive cells and correlation with clinical data was performed. It resulted that there is a great variability in positive cells for cytokines according to the harvest site; anyway, cytokines tend to be higher in patients carrying a joint prosthesis with polyethylene acetabular component and it is associated with plastic wear particles, even though there is no direct correlation between wear amount and cytokine levels. There is a statistically significant negative correlation between metal wear and a cytokine (IL-6); cytokines levels do not depend on the implant time to failure and do not correlate with pain score. As expected, cytokines levels tend to be lower in subjects being treated with non-steroidal antiinflammatory drugs. It can be concluded that plastic wear is the factor inducing the highest cytokine levels in the tissues around the prosthesis at the interface; cytokines that are an indicator of osteolysis risk.

Adult↗
PubMed1999

[Towards a pain-free hospital. A project and a campaign for the improvement of health care].

This article outlines the project entitled "Towards a Pain Free Hospital" which aims to make both citizens and health sector workers more aware of the problem of pain in hospitalised patients. The project is already under way in some countries and is being implemented in others. It has been introduced into the local Health Authority Hospital of Vicenza for the first time in Italy and will later be introduced into other Italian hospitals. The article deals with the various initiatives which make up the project and the methods used to involve those assisting the patient in pain.

Health Promotion↗
PubMed1998

In vitro sister chromatid exchange induced by glass ionomer cements.

The genotoxicity of three glass ionomer cements used in dentistry, manufactured by American (Vitrebond), Japanese (Fuji I), and European (Ketac Cem) companies were examined. The cement components were mixed according to the manufacturers' instructions and allowed to set for two defined times: 1 h or 1 week, before extracting them, as established by ISO standard 10993 part 12. To highlight sister chromatid exchange during mitosis, the extracts then were tested with human peripheral lymphocytes in the presence or absence of metabolic activation with S9 mix. The test performed was a genotoxicity test as provided for in standard EN 30993 part 3. Vitrebond resulted in direct genotoxicity and was strongly cytotoxic both in the extracts performed at 1 h and those at 1 week if they were allowed to set without photoactivation. Fuji I was noncytotoxic and showed only uncertain indirect genotoxicity in the extracts at 1 h; genotoxicity was not present in the extracts at 1 week. Ketac Cem cement was not genotoxic nor was it cytotoxic either at 1 h or 1 week. The authors concluded that of the three cements tested the European cement Ketac Cem passed one of the tests suggested by the EEC standard for assessing genotoxicity.

DNA Damage↗