Biomedical subjects

M Fini

Publications and source records attributed to M Fini.

At least 127 records · Page 7Linked to original sources

PubMed2000

Discriminant capacity of quantitative ultrasound versus dual X-ray absorptiometry to determine cancellous bone loss in ovariectomized rats.

The capacity of dual x-ray absorptiometry and quantitative ultrasound to discriminate bone loss and to predict the mechanical and microarchitectural properties of cancellous bone in an animal model of osteopenia was evaluated. Thirty-five female Sprague-Dawley rats (10 months old) were randomized into three groups: baseline group, 10 rats killed at the beginning of the study; ovx group, 15 rats ovariectomized; and sham group, 10 rats sham operated. At the beginning and end of the study, all the animals underwent osteosonography to record the proximal tail (C3 vertebra) bone speed of sound. Sixteen weeks after surgery, the animals were euthanized and the L5-6 lumbar vertebrae of each rat were excised for densitometric, biomechanical (compression test), and histomorphometric studies. Significant differences were found among the groups for final speed of sound (p = 0.01). The L5 bone mineral density of the ovx group decreased by 12.1% (p = 0.049) and 12.6% (p = 0.035) compared, respectively, with baseline and sham groups. The biomechanical parameters of the ovx group decreased by 15-47% compared with the other groups, showing significant differences between the ovx and sham groups both for maximal stress (p = 0.026) and elastic modulus (p = 0.013). Histomorphometric parameters of the ovx group showed significant decreases in comparison with other groups. Logistic regression analysis showed that dual X-ray absorptiometry and quantitative ultrasound discriminate ovariectomized and healthy rats with a similar capacity, classifying correctly all rats used in the model in a range of 61-70%. This similar capacity seems to derive from two different capacities to detect bone changes. Dual X-ray absorptiometry, depending on bone mineralization and density, is able to detect modifications in bone stiffness and strength, confirmed also by the correlation with biomechanical data. On the contrary, quantitative ultrasound seems to depend more on cancellous bone microarchitecural changes because it is correlated to histomorphometric parameters.

Absorptiometry, Photon↗

PubMed2000

The effect of osteopenia on the osteointegration of different biomaterials: histomorphometric study in rats.

The osteointegration of Hydroxyapatite (HA), Titanium (Ti-6Al-4V: Ti), Zirconia (ZrO2), Alumina (Al2O3) and 2 biological glasses (AP40 and RKKP) was comparatively investigated in normal and osteopenic rats by means of histomorphometry. Thirty-six Sprague Dawley female rats were left intact (Group C) while 36 were ovariectomized (Group OVX). Group C and OVX were further divided into 6 subgroups. After 16 weeks all animals were submitted to the femoral implant of nails made of the above-mentioned materials. Eight weeks after implantation the animals were euthanized, the femurs were harvested for histomorphometric analysis. The data showed that: (1) all the tested materials were biocompatible in vitro; (2) no significant differences existed in Affinity Index (AI) of Group C; and (3) results from paired comparison applied to the AI showed significant differences among the Groups C and OVX. The AI did not significantly change among intact groups, while it significantly decreased when some materials were implanted in OVX subgroups (AP40, ZrO2 and Ti-6Al-4V: p < 0.0005, p < 0.05 and p < 0.01). It is confirmed that bone mineral density is a strong predictor of the osteointegration of an orthopedic implant and that the use of pathological animal models is necessary to completely characterize biomaterials.

Journal Article↗

PubMed2000

Right ventricular dysfunction after thrombolysis in patients with right ventricular infarction.

BACKGROUND: Right ventricular (RV) infarction is frequently associated with highest risk of death and major complications. Doppler echocardiography can be useful in the diagnosis of RV involvement. The goal of this study was to evaluate Doppler echocardiography features associated with RV involvement and a poor prognosis. METHODS: Two-dimensional Doppler echocardiography was performed before and after thrombolysis in 108 consecutive patients with an RV infarction. The bedside examination was performed before and 2 to 3 hours after thrombolytic therapy, and repeated after 1 and 7 days. All patients underwent coronary angiography after 20 days, and the perfusion of the coronary-related artery (> thrombolysis in myocardial infarction [TIMI] 3 grade) was evaluated. RESULTS: Patients were divided into 2 groups according to the recovery of global and regional RV function after thrombolytic therapy. In the group of patients who showed a normalization or improvement of RV wall motion (as assessed by RV wall motion score index), we found a TIMI grade III perfusion in 78% of patients. The analysis of interatrial septal motion and interventricular septal motion showed a normalization in all reperfused patients. Major complication and deaths were more frequent in patients with echocardiographic findings of RV dysfunction persisting after thrombolytic therapy. CONCLUSION: In patients with RV infarction treated with thrombolysis, persistent RV dysfunction is associated with a higher risk for the development of major cardiac complications and death.

Aged↗

PubMed2000

Coupled plasma filtration-adsorption in a rabbit model of endotoxic shock.

OBJECTIVE: To test the hypothesis that nonselective adsorption by a hydrophobic resin of cytokines and other proinflammatory mediators could improve 72-hr survival in a rabbit model of endotoxic shock. DESIGN: Prospective, randomized, controlled animal trial. SETTING: Animal care facility at a research institution. SUBJECTS: A total of 109 New Zealand white male rabbits. INTERVENTIONS: Anesthetized rabbits were cannulated with indwelling femoral arterial and venous lines. Septic shock was induced by a single intravenous injection of Escherichia coli lipopolysaccharide. The dose was experimentally assessed in 40 rabbits receiving 1.0, 0.5, 0.1, and 0.05 mg/kg body weight to determine LD80 at 72 hrs. Extracorporeal circulation consisted of plasma filtration coupled with passage of the plasma filtrate through a hydrophobic sorbent and reinfusion into the venous line. The extracorporeal treatment lasted for 3 hrs. Rabbits injected with endotoxin (0.05 mg/kg) were submitted to plasma filtration with (19 rabbits) or without (20 rabbits) sorbent adsorption. As controls, rabbits injected with vehicle alone were treated with plasma filtration (ten rabbits) or without (ten rabbits) sorbent adsorption. Ten rabbits were monitored under anesthesia to determine basal survival. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of endotoxin, bioactive tumor necrosis factor, resin-adsorbed platelet-activating factor, mean arterial pressure, base excess, and white cell count were assessed and a global severity score was established. At 72 hrs, cumulative survival was significantly (p = .0041) improved in septic rabbits treated with coupled plasma filtration-adsorption. Circulating tumor necrosis factor bioactivity remained similar in control and treated rabbits. Biologically significant amounts of platelet activating factor were eluted from the sorbent during the entire treatment time. The severity score inversely correlated with survival (p < .001). CONCLUSIONS: Coupled plasma filtration-adsorption improved survival in a rabbit model of endotoxic shock. Coupled plasma filtration-adsorption may be an extracorporeal treatment capable of removing structurally different inflammatory mediators associated with sepsis.

Animals↗

PubMed2000

Assessment of bone architecture with ultrasonometry: experimental and clinical experience.

Over the last decade, ultrasound technology has been introduced as a method of analysing bone tissue in clinical practice, and several studies have compared various ultrasound devices with dual-energy X-ray absorptiometry (DXA). Unlike DXA, the ultrasound technique is not limited to the measurement of bone density - it also has the potential to provide information on the mechanical and architectural characteristics of bone. The first generation of ultrasound devices used the speed of sound and attenuation of the ultrasound signal to obtain information on bone mineral content. Second generation ultrasound devices, which analyse the ultrasound signal received, permit the study of bone structure and elasticity, in addition to its mineral content, in both experimental studies and clinical practice. This is accomplished by signal processing analysis, the study of backscattering and the application of Biot's theory. This approach to the study of bone tissue represents the future for the development of ultrasound technology for use in clinical practice.

Absorptiometry, Photon↗

PubMed2000

In vitro pathological model of osteopenia to test orthopaedic biomaterials.

The association of in vitro tests and in vivo bone implants, has significantly improved the characterization of biomaterials for orthopaedic devices before their clinical use. However, neither cell cultures nor most animals models used for these tests entirely reflect the clinical conditions in which biomaterials are implanted. Pathological animal models are considered to substantially improve our knowledge of osteointegration of biomaterials; for this reason researchers increasingly use aged, osteopenic or arthritic animals in their experimental tests. The development of "pathological cell cultures" would also be of great importance for the study of biomaterials. It would allow a complete material evaluation, beginning with a biocompatibility test to a more finalized and specific preclinical evaluation. The present study, looks at the possibility of using cell culture methodology for the improvement of in vitro biomaterials characterization in the case of osteopenia. Cultures derived from normal (NB-OST) rats were compared to those of osteopenic (OB-OST) rats, by testing the osteoblasts against common parameters of characterization. Moreover, the reaction of these cultures to two biological glasses of known in vivo behavior (both in normal and osteopenic bone) by means of parameters on biocompatibility and bone formation index, was evaluated. Our results showed that there was no evidence of differences between the NB-OST and OB-OST cultures. After 6 days of culturing, the bioglass that did not osteointegrate in osteopenic animals, did not induce cytotoxicity in NB-OST, but a significative reduction of viability and Osteocalcin level in OB-OST was observed. We think that these data should stimulate researchers to develop further tests in order to improve preliminary in vitro comprehension on biomaterials.

Alkaline Phosphatase↗

PubMed2000

Biostimulation of human chondrocytes with Ga-Al-As diode laser: 'in vitro' research.

The aim of this study was to verify the effects of laser therapy performed with Ga-Al-As Diode Lasers (780 nm, 2500 mW) on human cartilage cells in vitro. The cartilage sample used for the biostimulation treatment was taken from the right knee of a 19-year-old patient. After the chondrocytes were isolated and suspended for cultivation, the cultures were incubated for 10 days. The cultures were divided into four groups. Groups I, II, III were subject to biostimulation with the following laser parameters: 300 J, 1 W, 100 Hz, 10 min. exposure, pulsating emission; 300 J, 1 W, 300 Hz, 10 min. exposure, pulsating emission; and 300 J, 1 W, 500 Hz, 10 min. exposure, pulsating emission, respectively. Group IV did not receive any treatment. The laser biostimulation was conducted for five consecutive days. At the end of the treatment, the Calcium, Alkaline Phosphate, MTT tests and proteoglycan were performed to assess cell metabolism and toxicity level. The data showed good results in terms of cell viability and levels of Ca and Alkaline Phosphate in the groups treated with laser biostimulation compared to the untreated group. The results obtained confirm our previous positive in vitro results that the Ga-Al-As Laser provides biostimulation without cell damage.

Adult↗

PubMed2000

Assessment of low-power laser biostimulation on chondral lesions: an "in vivo" experimental study.

The purpose of this study was to evaluate whether intraoperative laser biostimulation can enhance healing of cartilaginous lesions of the knee. Surgery was performed on eighteen rabbits: a bilateral chondral lesion of 1.25 +/- 0.2 mm in length and 0.8 +/- 0.2 mm in width was created in the femoral medial condyle with a scalpel. The lesion in the left knee of each animal was treated intraoperatively using the diode Ga-Al-As 780nm. laser (300 Joules/cm2, 1 Watt, 300 Hertz, 10 minutes), while the right knee was left untreated, as control group. The animals were divided into three groups, A, B and C, according to the survival time after surgery, two, six and twelve weeks, respectively. The explants from the femoral condyles, both treated employing laser energy and left untreated, were examined histologically. Results showed a progressive filling with fibrous tissue of the cartilaginous lesion treated with laser irradiation, while no changes in the original lesion of the untreated group were observed at the end of the study. Maybe, in this experimental research, underexposure to laser irradiation was the cause for the absence of the necessary conditions for biostimulation.

Animals↗

PubMed2000

Osteochondral lesion repair of the knee in the rabbit after low-power diode Ga-Al-As laser biostimulation: an experimental study.

The purpose of this study was to evaluate whether low-power laser biostimulation of the osteo-chondral lesions of the knee could by itself reduce repair healing time. Surgery was performed on eighteen rabbits; a bilateral osteo-chondral lesion of 2.5mm in diameter and 2mm depth was created in the femoral medial condyle with a drill. The left knee of each animal was treated intraoperatively using the diode Ga-Al-As laser (780nm) with the following parameters: 300 Joules/cm2, 1 Watts, 300 Hertz, 10 minutes; the right knee was left untreated, as control group. The animals were divided into three groups, A, B and C, according to the survival time after surgery, two, six and twelve weeks, respectively. The explants from the femoral condyles, either treated employing laser energy or left untreated, were examined histomorphometrically. Results after laser treatment showed faster healing of the lesion at week 2 (p=0.043) and an overall improvement in cellular morphology (p=0.044), while a more regular aspect of the osteocartilaginous tissue was observed at week 12 (p=0.004). A relationship between laser biostimulation properties and healing of the osteo-chondral defect has been demonstrated.

Aluminum↗

PubMed2000

The ovariectomised sheep as a model for testing biomaterials and prosthetic devices in osteopenic bone: a preliminary study on iliac crest biopsies.

A histomorphometric and ultrastructural evaluation on sheep iliac bone was performed. Six sheep were ovariectomised (OVX Group) and 6 were left intact (Sham-aged, Control Group). An iliac crest biopsy was performed randomly in 6 animals at the beginning of the study, then, in all the animals, after 12 and 24 months. A significant decrease in trabecular bone volume, trabecular thickness (p<0.0005) and cell volume (p<0.005) was observed in OVX animals. A modest decrease in trabecular number and osteoid thickness together with an increase in trabecular separation were observed in OVX animals at 12 and 24 months. The osteoid volume showed a significant difference (p<0.05) between the groups. In OVX animals, at 12 months, Scanning Electron Microscopy revealed an enlargement of the trabecular space and a progressive replacement of bone matrix with adipose tissue. These signs were accentuated at 24 months. In conclusion, OVX sheep showed a loss of trabecular bone starting at 12 months after ovariectomy. The developed osteopenic state may be considered as a useful tool when doing research on biomaterial osteointegration.

Analysis of Variance↗

PubMed2000

A resorbable biomaterial shaped as a tubular chamber and containing stem cells: a pilot study on artificial bone regeneration.

In a previous study, we showed how healing of non-union defects in rabbit radii can be achieved by means of a tubular resorbable chamber, in comparison with untreated defects. In the present study, we placed bone marrow stem cells inside the chamber. Bone marrow was obtained by percutaneous aspiration from the iliac crest in 9 adult New Zealand rabbits. Stem cells were separated by the centrifugation technique. In the same animals, a defect of 10 mm was created in both radii. On the left side, the defect was treated with the poly-DL-Lactide chamber, in which a suspension of autologous cells was injected; on the right side, only autologous cells were used. Radiological and histomorphometric data were compared within this study as well as with the results of our previous study. At 3, 6 and 9 months, there was no healing on the right side..On the left side, progressive bone formation with reunion of the stumps was observed in the chamber. We conclude that stem cells can accelerate bone healing when contained in the tubular chamber.

Animals↗

PubMed2000

Biomaterials in spinal fixation. An experimental animal study to improve the performance.

Different pedicle screws were biomechanically and morphologically studied and compared through the use of an animal model to determine their efficacy and resistance in spinal fixation. The principal objective was to compare biomechanical and histomorphological aspects of HA-coated screws to uncoated ones. Fourty-eight cylindrical transpedicular self-tapping screws divided into three groups of sixteen each were employed; Group A: stainless steel screws; Group B: titanium screws; Group C: HA-coated titanium screws. The screws were implanted bilaterally and randomly into the L3, L4, and L5 pedicles of eight adult mongrel sheep. The final insertion torque was measured in all the implants. After one and four months, upon euthanization, four samples per group were extracted from the surrounding bone and the screw extraction torque was measured. The remaining samples were examined and processed for histological and histomorphological evaluations. No differences were observed at one month among the extraction torque of the three groups. After four months the only significance between insertion and extraction values was for the HA group, i.e. p=0.001. Comparing the extraction torque values of the three groups after four months of healing, the HA-coated group showed a greater than twofold increase (p<0.0005). No differences were observed at one month among the percentages of bone-implant contact in the three groups. After four months the percentage was significant only for the C group (p<0.0005). At four months a correlation was found between the morphological and the biomechanical data of group C (p<0.0005). The use of hydroxyapatite-coated screws could act as an effective method to improve the bone-implant interface, thus obtaining a strong fixation of the implant independently of the arthrodesis achieved with bone graft.

Analysis of Variance↗

PubMed1999

Measurement of insertion torque of tapered external fixation pins: A comparison between two experimental models.

The aim of this study was to compare an in vitro versus an ex vivo experimental model to test the insertion torque of two different types of external fixation pins. A torque measuring machine was developed in order to perform accurate measurements. Forty tapered pins made of stainless steel were utilized. Half of the pins were plasma-spray coated with hydroxyapatite (HA) and the other half remained uncoated. For the in vitro model 20 cylinders were used that were made of synthetic polymer according to ASTM standards. For the ex vivo model 10 fresh femora harvested from adult sheep were used. All the pins were implanted after predrilling, and insertion torque was measured. Statistical analysis of the in vitro versus the ex vivo model showed significant differences in both coated (p < 0. 0005) and uncoated (p = 0.002) external fixation pins. These results may be due to the surface roughness that caused significant friction between the HA coating and the polyvinylchloride in the in vitro model. The significant difference between the in vitro and ex vivo results lead us to state that the in vitro model does not realistically simulate the behavior of external fixation pins implanted in bone.

Animals↗

PubMed1999

The mechanical properties of fluoride-treated bone in the ovariectomized rat.

The effect of fluoride therapy on the osteopenic bone of the ovariectomized rat was studied by comparing the densitometric and biomechanical data. Forty retired breeder female Sprague-Dawley rats aged 10 months were randomly divided into five groups. One group (Group A) was killed at the beginning of the study and was used as a baseline. Three groups were ovariectomized and one was sham-operated (Group B) and observed for the same period as a sham-aged group. A group of ovariectomized rats was used as a sham therapy control (Group C) and received only deionized drinking water; the other two groups (F1 and F2) received L-glutamine monofluorophosphate and calcium at a rate of 1:30 F/Ca at different doses by gavage (0.57 mg F/17 mg Ca per kg/day-Group F1; 0.21 mg F/6.30 mg Ca per kg/day-Group F2). Densitometric and biomechanical (compression and three-point bending test) assays, X-ray diffraction, and Fourier transformed infrared spectroscopy were performed on femoral specimens. Biomechanical data showed that the femoral heads of Group F2 required a significantly greater energy-to-failure than Group C (P < 0.05) as well as treated femoral diaphysis when compared with the others (P < 0.01). Significant increases in the elastic modules were observed in fluoride-treated groups (P < 0.001) when compared with other groups. Diffractometric and spectroscopic data showed the presence of fluorine-apatite in both treated groups with a high component of carbonates. Also, fluoride therapy causes an increase of bone stiffness due to the presence of fluoroapatite. It seems to produce two opposed properties in the osteopenic rat bone: a higher resistance to compression loading and a greater frailty to flexion loading.

Animals↗

PubMed1999

Xenogenic demineralized bone matrix: osteoinduction and influence of associated skeletal defects in heterotopic bone formation in rats.

Demineralized bone matrix (DBM) was ectopically implanted in 36 male Wistar rats. In 18 of the animals a bone defect in the femoral condyles was also created: the left was filled with DBM and the right was left empty as a control. The animals were killed after 2, 4 and 6 weeks and new bone was histologically evaluated, comparing ectopic bone formation with or without distant bone injury. Results showed: (1) osteoinductivity of xenogenic DBM, and (2) earlier mineralization of ectopically implanted DBM in the group with associated skeletal injury. Our results show that xenogenic bone matrix acts as an osteoinductive material and that skeletal injury improves osteogenesis at distant sites.

Animals↗

PubMed1999

Effects of essential amino acids and lactose on bony fractures and defects in rabbits: a preliminary histomorphometric study.

An experimental study was performed in order to test the possibility of improving bone repair with the administration of a drug (Calciofix, Farmaceutici Damor SpA, Naples, Italy) containing essential amino acids and lactose. Fifty rabbits were submitted to an open transversal fracture of the left fibula and to a right femoral condyle defect. They were left untreated or treated daily with the drug orally and were divided into subgroups depending on the experimental time: 15, 30, 40, 50, 60 days. Histomorphometric data showed a significantly faster healing rate in treated animals compared with untreated ones. Firstly, on day 30 there was a significantly larger amount of cartilage in the control bone callus (P < 0.01). On day 50 a significant difference existed between trabecular and lacunar percentages in the two subgroups (P < 0.0005). At 60 days no significant differences were observed, but bony trabeculae had become more oriented parallel to the long axis of the bone in treated animals. Secondly, after 15 days the defect area was significantly smaller in treated animals than in the untreated ones (P < 0.01). At 30 and 40 days, respectively, significant differences existed between the two subgroups in connective tissue and mature bone percentages (P < 0.01 and P < 0.001). Our results seem to demonstrate that the drug significantly accelerates the rate of bone formation in fractures and bone defects in rabbits.

Amino Acids↗

PubMed1999

In vitro and in vivo behaviour of Ca- and P-enriched anodized titanium.

The influence of different surface preparations on titanium biocompatibility and bone integration was evaluated. Commercially grade 2 titanium rods (diameter 2 mm, length: 3 mm), vacuum annealed and hydrofluoric acid etched was selected for its promising surface characteristics to achieve good direct osseointegration. Some rods were surface modified by Anodic Spark Discharge anodization and a thin layer (approximately 5 microm) of amorphous TiO2 containing Ca and P (Ti/AM) was obtained. Some of the Ti/AM specimens underwent a further hydrothermal treatment to produce a thin outermost layer (approximately 1 microm) of hydroxyapatite (Ti/AM/HA). Cytotoxicity tests (direct contact: ISO 10993-5) showed good cytocompatibility for all tested samples. Ti and tissue culture substrate + DMEM control, respectively, were associated with a significant higher proportion of attached cells than Ti/AM and Ti/AM/HA (P < 0.0005), but this was in the normal range of 10-20% of unattached cells for cytocompatible materials. Histomorphometric analysis conducted on samples inserted in the cancellous bone of distal femoral epiphysis of Sprague-Dawley rats gave the following results at 4 and 8 weeks: Affinity index (AI%) data proving the surface osteconductive properties of non-anodized acid etched Ti (AI-4 weeks: 67.1 +/- 17.0%; AI-8 weeks: 74.8 +/- 11.5%). Ti/AM samples showed the lowest values (AI-4 weeks: 45.8 +/- 15.9%; AI-8 weeks: 68.5 +/- 13.6%) while the best performances of the Ti/AM/HA samples (AI-4 weeks: 60.4 +/- 21.8%; AI-8 weeks: 79.5 + 9.37%) indicated that hydroxyapatite allowed a higher bone to implant contact respect to Ti only. Further investigations should be performed in order to better understand the mechanism of observed in vitro behaviour and to achieve information on long-term osseointegration process.

Analysis of Variance↗

PubMed1999

Polylactide bioabsorbable polymers for guided tissue regeneration.

OBJECTIVE: Guided tissue regeneration is a procedure to improve tissue repair, which creates an optimal environment for the intrinsic growth ability of tissues. METHODS: A prerequisite for guided tissue regeneration is the availability of materials with suitable physicochemical and biocompatibility properties for the preparation of the devices. We investigated bone and peripheral nerve guided tissue regeneration, making two conduits from poly[L-lactide-co-6-caprolactone] (PLLC--peripheral nerve) and with poly [DL-lactide] (PDLLA--bone) with different features. After the polymer synthesis and chemical characterization, the conduits were evaluated in vivo in rat sciatic nerve gaps and in rabbit radius defects. RESULTS: The results demonstrated good biocompatibility of both polymeric conduits. A good axonal regeneration and the restoration of the nerve trunk continuity, similar to that observed with autologous grafts has been obtained with PLLC conduits, that slowly degrade in about 6 months. PDLLA conduits protected the bone defect against the invasion of surrounding soft tissues; an effective bone growth bridging the defect was observed in their lumen. CONCLUSION: These results confirm the versatility of polylactides as biomaterials and will encourage further investigations on hard and soft tissues.

Absorption↗