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Biomedical subjects

R Giardino

Publications and source records attributed to R Giardino.

At least 19 recordsLinked to original sources
PubMed1999

Reconstruction of extensive long-bone defects in sheep using porous hydroxyapatite sponges.

The capacity of hydroxyapatite (HA) implants to support large defect repair in weight-bearing long bones of large size animals was investigated. Diaphyseal resections 3.5 cm of the tibia were performed in five adult sheep. They were substituted with HA macroporous ceramic cylinders anatomically shaped, and an external fixator was assembled. The sheep were sacrificed at 20, 40, 60, 120, and 270 days after surgery, respectively. Histology and micro X-ray study of resected implants and adjacent tissues showed proper integration of ceramic with newly formed periosteal bone as early as 20 days after surgery. In one sheep, the external fixator was removed 5 months after surgery. The animal gained the ability to walk with no functional impairment until it was sacrificed 4 months later. At this time, extensive integration of ceramic with bone was detected radiographically and confirmed by a morphological study of the resected sample. Our data indicate that large defects in a weight-bearing long bone can be repaired to the extent necessary for full functional recovery in large animals. These data set the stage for further intervention on material properties as well as for preliminary attempts to use ceramic prostheses for reconstruction of large bone defects in humans.

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↗
PubMed1998

Laser Doppler evaluation of microcirculation behaviour during an ischaemia-reperfusion injury.

Laser Doppler flowmetry (LDF) was tested in an experimental ischaemic model on rat limbs to evaluate the degree of ischaemia and to find a possible correlation with values obtained with this device and prognosis. Under general anaesthesia, 40 Wistar rats were submitted to 4 h and 30 min of ischaemia of the left hind limb. Ten rats formed the control group (group 1). Two enzymes, native superoxide dismutase (SOD) and SOD modified with polyethylene glycol, were employed in 15 rats each (groups 2 and 3). Data were collected by means of LDF both in the sole and muscles before ischaemia (steady state), during ischaemia and at the beginning of reperfusion, and only in the sole after 1 h of reperfusion. A range of predictive (95%) perfusion values (PU) for limb healing or necrosis was identified at the beginning of reperfusion. During ischaemia, PU changed from 0 to 10, both in the sole and in the muscle. A three-factor ANOVA (site, group, time) did not show interaction of these factors with PU (F = 1.655; p = 0.195), even if every single effect was significant (p < 0.0005). A two-factor ANOVA (group, time) showed a significant interaction of these factors with PU (F = 4.079; p = 0.019). The logistic regression between the reperfusion PU of each site and the survival of the limb was observed at the beginning and after 1 h of reperfusion in the sole only. Furthermore, a correlation between sole and muscle PU at the steady state and at the beginning of the reperfusion period was observed. The results showed the effectiveness of LDF, which can be considered a quite reliable tool to evaluate the degree of ischaemia and to have a good correlation with prognosis in this kind of experiments.

Animals↗
PubMed1998

In vitro osteoinduction of demineralized bone.

Among numerous available materials for osseous repair and reconstruction, those presenting osteoinductive characteristics and promoting bone regeneration are preferable. Fresh autologous bone is one of the most effective, but it has some disadvantages and risks. Demineralized bone matrix (DBM) is considered to be a valid alternative, because it seems to show osteogenic potential, ascribed to the presence of bone morphogenetic proteins. In addition it can be prepared without difficulty and preserved without losing osteoinductive properties. The aim of the study was to evaluate the osteoinductive ability of xenogenic DBM, by testing DBM powder obtained from rabbit long bones, in cell culture of murine fibroblasts, alone or associated with electromagnetic field (EMF), that are known to exhibit biologic effects on cells: in particular they are used in orthopedics to improve bone formation. At the end of experiment, alkaline phosphatase (ALP) activity, calcium levels and cell proliferation and morphology were evaluated. A statistically significant stimulation of ALP activity and cell proliferation and a morphological change of fibroblasts were found. The results obtained show how DBM and EMF have different effects on cells, and that together they have synergic action toward bone induction.

Animals↗
PubMed1998

In vitro experimental research of rabbit condrocytes biostimulation with diode laser Ga-Al-As: a preliminary study.

The scope of our study was to verify the effects of a new diode laser device with active material composed of Gallium, Aluminum and Arsenic (Ga-Al-As) configured as MOCVD (780 nm., 3000 mW) for the biostimulation of the cartilage cells in vitro. The condrocytes cells, withdrawn from the cartilage of the medial condyle of the femur of the rabbit, were cultivated, incubated and subject to biostimulation treatment with the laser. The condrocytes cells were placed in 24 Petri dishes at the concentration of 0.25 x 10(5)/ml and divided into 4 groups: 3 group (I, II, III) were treated with the laser and the fourth group (IV) was used as the control group. At the end of the treatment, all four groups, were evaluated with a MTT test and a cell count of the condrocytes cells. Group III (300 J, 1 Watt, 300 Hz, 10' of exposure time with a pulsating emission) provided the best results in terms of cell viability (MTT test) and for the number of cells found in the dishes when compared to the other treated groups and the control group. The results obtained with the use of this new diode laser Ga-Al-As device in the biostimulation of the cartilage tissue, permits us to consider the use of this device clinically.

Aluminum↗
PubMed1998

Absorbable screws through the greater trochanter do not disturb physeal growth: rabbit experiments.

We studied the effect of implantation of self-reinforced polyglycolic acid (SR-PGA) screws through the greater trochanter in rabbits. 15 rabbits aged 10 weeks had an SR-PGA screw inserted through the left trochanter physis. A similar drilling was made through the right greater trochanter without screw implantation. The animals were assigned to 3 groups of 5, and were killed after 1, 2 or 3 months. Radiographs of both femurs were obtained monthly and the articulo-trochanteric distance and the neck-shaft angle were measured. After killing the animals, a histological study was performed. The drilling on the right trochanter generated a bony bridge in all the animals. The SR-PGA screws did not give rise to an epiphysiodesis. The progressive peripheral degradation of the implants gave rise to the formation of only modest bridges, which were smaller in size than those observed in the control trochanter. Our findings suggest that absorbable PGA screws implanted through a growth plate cause only minor bone formation and no epiphyseodesis.

Animals↗
PubMed1998

pO2 measurement in an experimental model of patellar tendon autograft pro-anterior cruciate ligament.

Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of the patellar tendon, ten enter this study. The purpose was to find a possible relationship between tissue pO2 and healing processes considering also the biomechanical and histomorphological aspects of the grafts. Four of them were sacrificed under general anaesthesia after 6 months, and six after 1 year in order to perform tissue pO2 measurement and an analysis of microvessel density on specimens of the normal ACL and the graft. Our data showed higher pO2 values of the autografts after 6 months. After 1 year the data was comparable to those of native ACL. This was confirmed by a microvessel count of the histological specimens and the data was in relationship to biomechanical and histomorphological analysis. Tissue pO2 can be observed and recorded in "in vivo" ACL, and patellar tendon used as graft, with no injury to their integrity. The monitoring system might be considered as an experimental tool for indirect controls of the anterior cruciate substitutes.

Animals↗
PubMed1998

Gas exchange threshold as a predictor of severe postoperative complications after lung resection in mild-to-moderate chronic obstructive pulmonary disease.

Low exercise capacity is considered predictive for postoperative complications or death after thoracic and general surgery. However, in recent literature no agreement has been found about the predictive cut-off values for preoperative exercise parameters. The aim of this work was to investigate whether peak oxygen consumption (V'o2) and noninvasive anaerobic threshold (AT) determined by gas exchange threshold (GET) can be reliable preoperative predictors of mortality and morbidity after lung resection in patients with mild-to-moderate (forced expiratory volume in one second (FEV1) > 50% predicted) chronic obstructive pulmonary disease (COPD). Fifty tour COPD patients were studied before lung surgery: 12 had severe complications, 16 had mild and 26 had no complications. Peak V'O2 sensitivity and specificity in predicting severe postoperative complications were 41.6% and 95.5% respectively (using 75% of the predicted value as cut-off), while for GET they were 91.6% and 97.6% respectively (using 14.5 mL.kg-1.min-1 as cut-off value). Only one patient (3.5%) with a peak V'O2 > 20 mL.kg-1.min-1 suffered severe complications. On the other hand 11 out of the 26 patients (42.3%) with peak V'O2 < 20 mL.kg-1.min-1 had serve complications. In patients with peak V'O2 < 20 mL.kg-1.min-1, 11 out of 12 (91.6%) with a GET < or = 14.5 mL.kg-1.min-1 suffered severe complications, whereas 15 out of 15 (100%) with a GET > 14.5 mL.kg-1.min-1 showed no or mild complications. In conclusion, peak oxygen consumption values > 20 mL.kg-1.min-1 can be considered a safe upper cut-off limit for pulmonary resection. In patients with a peak oxygen consumption value < 20 mL.kg-1.min-1, gas exchange threshold determination can improve significantly the predictivity of a cardiopulmonary test for severe complications and must be routinely considered.

Adult↗
PubMed1998

A reabsorbable tubular chamber for the treatment of large diaphyseal bone defects. Experimental study in rabbits.

Twenty-five rabbits were used to test the healing of diaphyseal defects by means of a reabsorbable tubular chamber. In 20 animals a 10 mm gap was created in the left radius and bridged with a poly-L-lactide chamber (experimental side). The same defect was created on the right radius, remaining untreated (control side). In the remaining 5 animals, the right radius was left intact and they were used only for biomechanical tests at 12 months. X-rays and histomorphometry showed no bone repair at the control side while the inner surface of the chamber was progressively lined by neoformed bone (75% of the normal cortical thickness). Biomechanical data demonstrated that elastic modulus and ultimate stress were not significantly different in both experimental and intact radii. The chamber, by preventing the passage of soft tissues and creating a close space for intrinsic repair factors, seems to be a suitable device for the repair of long bone defects.

Analysis of Variance↗
PubMed1998

Comparison among three different biocoatings for orthopaedic prostheses. An experimental animal study.

One-hundred-eighty cylindrical monocortical titanium implants, 4mm diameter and 12mm long, with three different coatings: fluorohydroxyapatite (group A), hydroxyapatite (group B), and titanium oxide (group C), all applied by vacuum plasma spray were bilaterally, randomly implanted into the femurs and tibiae of twelve adult mongrel sheep. The sheep were divided into four groups (1, 2, 3 and 4) numbering three sheep each. Sheep of groups 1, 2, 3 and 4 were euthanized at two weeks, one month, three and nine months after implantation, respectively Biomechanical and histomorphological analysis were performed. Extraction torque increased over time in all groups until the nine months period. At all the studied periods, the bone-implant contact was higher in Groups A and B compared to Group C. However, only at nine months did this difference reach statistical significance (p<0.005 comparing Groups A and B to C). The results of this study show that all the three coatings could be recommended for clinical applications.

Animals↗
PubMed1997

Experimental evaluation of a resorbable intramedullary plug for cemented total hip replacement.

In order to evaluate degradation kinetics and biocompatibility of a resorbable poly(D,L-lactic acid) (PDLLA) plug for total cemented hip prostheses, an experimental in vitro and in vivo study was carried out. Degradation rate studies were performed in Ringer solution and after in vivo plug implantation in the femoral medullar cavity of rabbits. In vitro biocompatibility was evaluated in murine fibroblast cell cultures. PDLLA plugs showed faster degradation kinetics in vivo than in vitro. Histological evaluations showed that PDLLA completely disappeared in vivo 26 weeks after implantation. Fibrous tissue in the medullar cavity was observed at 13 weeks, but no histological changes were observed after 26 weeks. Also, the in vitro tests showed good biocompatibility of the biomaterial. Our results show the possibility of considering this resorbable plug for clinical situations instead of the traditionally used plugs [polyethylene, poly(methyl methacrylate) or cancellous bone] due to its biocompatibility, degradation properties and simplicity of use.

Animals↗
PubMed1997

Biomaterials for orthopedic surgery in osteoporotic bone: a comparative study in osteopenic rats.

UNLABELLED: To evaluate orthopedic devices in pathological bone, an experimental study was performed by implanting Titanium (Ti) and Hydroxyapatite (HA) rods in normal and osteopenic bone. Twenty-four rats were used: 12 were left intact ( CONTROL: C) while the other 12 were ovariectomized (OVX). After 4 months all the animals were submitted to the implant of Ti or HA in the left femoral condyle (Ti-C, HA-C, Ti-OVX, HA-OVX). Two months later the animals were sacrificed for histomorphometric, ultrastructural and microanalytic studies. Our results show a significant difference between the Affinity Index (A.I.) of HA-C and Ti-C (77.0 +/- 7.4 vs 61.2 +/- 9.7) (p < 0.05). No significant differences were observed between the osteointegration of Ti-C and Ti-OVX (61.2 +/- 9.7 vs 48.2 +/- 6.7). Significant differences also exist between the osteointegration of HA-C and HA-OVX (77.0 +/- 7.4 vs 57.6 +/- 11.5) (p < 0.01). Microanalysis shows some modifications in Sulphur (S) concentration at the bone/biomaterial interface of the Ti-OVX group. Therefore our results confirmed the importance of biomaterials characteristics and of bone quality in osteointegration processes.

Animals↗
PubMed1997

[Effects of synthetic salmon calcitonin and alendronate on bone quality in ovariectomized rats].

BACKGROUND: The aim of this study was to assess the effect of calcitonin (CCT) and alendronate (ALN) on bone quality through histomorphometric, histological, densitometric and crystallographic evaluations in an experimental model of osteoporosis obtained in ovariectomized rats. METHODS: The animals were randomly assigned to the treatment with CCT (2 IU/kg/day, N-12) or with ALN (6 micrograms/kg/day, N-12) given subcutaneously, starting three months after ovariectomy: treatment lasted 60 days. Six rats untreated after ovariectomy and other 6 non ovariectomized (intact) were taken as controls. At the end of treatment the animals were sacrificed and femurs explanted for laboratory examinations. Results were evaluated by an ANOVA followed by the Tukey's test when appropriate. RESULTS: The histomorphometric analysis showed a significant increase of the trabecular bone volume and of the cortical bone thickness either with CCT and ALN in comparison with the ovariectomized untreated controls. Optic and electronic microscopy examinations suggest a higher bone remodeling after ALN than after CCT, but accompanied by areas of imperfect mineralization, and more irregular osteon and collagen fibres disposition. The densitometry carried out at the femoral head and diaphysis showed a similar bone mass increase following either CCT and ALN, but significantly higher in comparison to the untreated controls. At the diaphysis level ALN was superior in increasing the bone mass also when compared to the intact rats. The mineralogic exams showed that CCT acted on the re-elaboration of the mineral phase approaching the molar ratio Ca/PO4 to the physiological values typical of senescence, and crystallography revealed that the formation of hydroxyapatite crystals follows a physiological mineral redeposition: those phenomena were not observed for ALN. CONCLUSIONS: In conclusion both CCT and ALN could reduce the bone loss due to osteoporosis, by increasing the bone mass and thickness. Nevertheless the submicroscopic and chemical bone structure are less similar to the physiologic ones after treatment with ALN.

Alendronate↗
PubMed1997

An experimental pilot study of tacalcitol activities during modulation of parakeratotic skin features.

Establishing guidelines and experimental models preclinical and clinical evaluations of new agents for treatment, and/or prevention of human diseases has become a task of crucial importance. Psoriasis is such one disease holding great interest for dermatology owing to its high rate of incidence and complexity of treatment. However the absence of psoriatic lesions in animals and the inability to induce them, calls for experimental techniques both in vitro and in vivo. The purpose of this study was to evaluate experimentally the effects of tacalcitol on cell proliferation and differentiation process. Thereafter a human pilot study on psoriatic patients has been developed.

Administration, Topical↗
PubMed1997

Bioabsorbable polyphosphazene matrices as systems for calcitonin controlled release.

To provide a suitable delivery system for the calcitonin controlled release 80 mg bioabsorbable polyphosphazene matrices were obtained with entrapped 50 or 250 micrograms calcitonin. The in vitro behaviour demonstrated a release burst for about 24 hours, followed by a period of slow release of the peptide lasting for weeks. Matrices containing 250 micrograms calcitonin were implanted under general anaesthesia in osteoporotic female rats, while a group of animals (control group) received unloaded matrices. After thirty days a second batch of matrices was implanted in both groups to prolong the period of treatment until two months. The explanted matrices were histologically evaluated together with the surrounding tissues, and the dosage of the residual calcitonin was also performed. Results demonstrated the good biocompatibility of the system and the complete release of the calcitonin from the matrices 30 days after implantation. The therapeutic effect, after sixty days of treatment was confirmed by the better densitometric values observed in the femoral bone of treated animals than in controls.

Animals↗
PubMed1996

Effectiveness of a bioabsorbable conduit in the repair of peripheral nerves.

A new conduit made with a bioabsorbable copolymer, poly (L-lactide-co-6-caprolactone), was evaluated in an animal model as a guide for nerve regeneration. The conduit had an inner diameter of 1.3 mm and a wall thickness of 175 microns. Segments of length 1.2 cm were interposed between the proximal and distal stumps of transected ischiatic nerves in Wistar rats, bridging a nerve gap of 1 cm. All of the procedure was performed under general anaesthesia using microsurgical techniques. Controls were performed at 1, 3 and 6 months and it was demonstrated that the conduit was still undamaged after 30 d. Progressive signs of degradation appeared at 90 and 180 d. Nerve regeneration in the lumen was effective as confirmed by histological and electron microscopical investigations. These preliminary results emphasize the interesting properties of the conduit with regard to the achievement of a neural prosthesis.

Absorption↗