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Biomedical subjects

L Andrini

Publications and source records attributed to L Andrini.

15 recordsLinked to original sources
PubMed1998

The relevance of hydroxyapatite and spongious titanium coatings in fixation of cementless stems. An experimental comparative study in rat femur employing histological and microangiographic techniques.

Pure titanium rods plasma-spray coated with hydroxyapatite (HA) or porous titanium (Ti) of controlled roughness were implanted bilaterally in the distal femur of Sprague-Dawley rats to compare the extent of bone growth on the two types of coating. The relevance of other factors, like mechanical stability and biological adaptation of the bone to the insertion of a foreign body implant, were investigated in femora which were over-reamed (absence of primary fit) or reamed without insertion of the rod. Continuous tetracycline labeling for the first 30 days and for the last 2 weeks in the 90-day group was performed; histological/histometric, fluorescence and microangiographic studies were carried out on serial sections of the implanted and control femora. In the group of stable implants, HA-coated rods showed 90% integration versus 53% with Ti-coated implants (P < 0.001); in over-reamed implants neither surface bone growth nor endosteal fixation occurred, and both types of rods were surrounded by a thick layer of connective tissue. The study documented early adhesion of osteoblasts and direct deposition of bone matrix on the substrate, while on spongious titanium osteogenesis was observed only in proximity to the surface. Remodeling of the reactive, primary bone to mature, lamellar bone took the form of a capsule surrounding the implants and radial bridges connecting the latter to the endosteal surface. The number, height and thickness of these bridges appeared to be the factors determining implant stability, rather than the extent of the bony capsule on the perimeter of the implant. Integration was a function not only of mechanical conditions and surface geometry, but also of the biological response of the whole bone to changes in the vascularization pattern. The reported phenomena can be seen more easily in experimental models involving small rodents because of their fast bone turnover and revascularization, but it is expected that they take place, even at a lower speed, in clinical situations like cementless stems of total hip replacement.

Angiography↗
PubMed1998

The effects of bone resorption inhibitors on the growth plate and proximal tibial metaphysis of rats: clinical implications.

This study investigated the effects of diphosphonates at scalar doses in a high bone turnover structure, namely, the proximal tibial metaphysis of rats. Arrest of bone modeling was represented by cylindrical-shaped metaphyses, increased height of the perichondrial bone bark, and persistence of primary metaphyseal trabeculae; these changes were dose-related. Higher doses of the inhibitors produced extension of the growth plate and arrest of the mineralization process. The dose-related dissociation between the effects on bone resorption and mineralization allows the therapeutic use of this class of drugs.

Animals↗
PubMed1997

Gait patterns after anterior cruciate ligament reconstruction.

The aim of this study is to analyse the changes in select gait parameters following anterior cruciate ligament (ACL) reconstruction. The study was performed on 15 subjects who underwent ACL reconstruction by the bone-patellar tendon-bone technique. Gait analysis was performed using the Elite three-dimensional (3D) optoelectronic system (BTS), a Kistler force platform and the Telemg telemetric electromyograph (BTS). Kinematic data were recorded for the principal lower limb joints (hip, knee and ankle). The examined muscles include vastus lateralis, rectus femoris, biceps femoris and semitendinosus. The results obtained from the operated subjects were compared with those of 10 untreated subjects and 5 subjects without ACL damage. In the operated subjects the knee joint angular values regained a normal flexion pattern for the injured limb during the stance phase. The analysis of joint moments shows: (a) sagittal plane: recovery of the knee flexion moment at loading response and during preswing; (b) frontal plane: recovery of the normal patterns for both hip and knee adduction-abduction moments during the entire stance phase. The examination of ground reaction forces reveals the recovery of frontal component features. The EMG traces show the normal biphasic pattern for the operated subjects as compared to the untreated subjects. The results suggest that the gait parameters shift towards normal value patterns.

Adult↗
PubMed1997

The reaction to nailing or cementing of the femur in rats. A microangiographic and fluorescence study.

Bone reaction to cement and to a cementless stem was studied in the rat femur with histological fluorescence and microangiographic techniques. Periosteal and endosteal apposition, and consequent remodelling, appeared as a reaction to reaming rather than caused by cement or a cementless stem. Every change in bone began with proliferation, progression and orientation of the vessels. Endosteal apposition was absent in cemented femurs because the entire medulla was occupied by the acrylic cement, but remodelling of the subendosteal cortex followed medullary revascularisation which was far advanced after 90 days. In cementless stems, endosteal apposition of primary woven bone and remodelling was the basis for bony ingrowth and anchorage through bony bridges. Our results suggest that the pattern of blood supply is relevant to the structural organisation of mature lamellar bone around the implant. Cemented stems have maximum anchorage and stability as soon as they are inserted, but this decreases with time as revascularisation occurs. Cementless stems can reach maximum integration later after insertion, and revascularisation is less critical because they usually do not fill the canal completely.

Animals↗
PubMed1997

Pathology of disappearing bone disease: a case report with immunohistochemical study.

A case of disappearing bone disease of the proximal femur is reported with histopathological and immunohistochemical studies. There was a densely packed cellular tissue, positive to endothelial antibodies, in areas of massive bone destruction. A more differentiated vascular tissue was present where trabecular cancellous or cortical bone was preserved with only focal zones of accelerated bone remodelling. The self-limited course correlates well with two phases of evolution of the histopathological lesions with neoplastic-like proliferation of endothelial cells corresponding to the rapid and massive bone destruction, and a later differentiation of the cells in mature vascular structures, but still with accelerated bone resorption which is partly compensated by appositional activity.

Arthroplasty, Replacement, Hip↗
PubMed1997

The effects of mechanical forces on bones and joints. Experimental study on the rat tail.

We have used an experimental model employing the bent tail of rats to investigate the effects of mechanical forces on bones and joints. Mechanical strain could be applied to the bones and joints of the tail without direct surgical exposure or the application of pins and wires. The intervertebral disc showed stretched annular lamellae on the convex side, while the annulus fibrosus on the concave side was pinched between the inner corners of the vertebral epiphysis. In young rats with an active growth plate, a transverse fissure appeared at the level of the hypertrophic cell layer or the primary metaphyseal trabecular zone. Metaphyseal and epiphyseal trabeculae on the compressed side were thicker and more dense than those of the distracted part of the vertebra. In growing animals, morphometric analysis of hemiepiphyseal and hemimetaphyseal areas, and the corresponding trabecular bone density, showed significant differences between the compressed and distracted sides. No differences were observed in adult rats. We found no significant differences in osteoclast number between compressed and distracted sides in either age group. Our results provide quantitative evidence of the working of 'Wolff's law'. The differences in trabecular density are examples of remodelling by osteoclasts and osteoblasts; our finding of no significant difference in osteoclast numbers between the hemiepiphyses in the experimental and control groups suggests that the response of living bone to altered strain is mediated by osteoblasts.

Age Factors↗
PubMed1993

[A case of human subcutaneous dirofilariasis in the Turin hills].

The literature about human dirofilariasis is briefly reviewed with particular reference to the Italian epidemiology, and a case of subcutaneous localization of living Dirofilaria Repens is described. The infestation occurred on the Turin hills. The occurrence of dirofilariasis in a hilly zone is pointed out, because the most common occurrence in Piedmont has been reported from rice zones.

Adolescent↗
PubMed1981

[Pharmacokinetic and clinical evaluation of cefoxitin].

An investigation conducted on healthy volunteers showed that cefoxitin quickly reaches high plasma concentrations, and is almost completely excreted via the urine within 6 hours. In a series of 21 cases treated with 2 g i.v. in 100 ml of a 5% glucose solution two or three times a day, a clinical cure was achieved in 20, and marked improvement in the remaining patient.

Bacillus subtilis↗
PubMed1981

[Kinetic and clinical study of bacampicillin].

A mean plasma concentration curve, with peaks within the first hour and moderate individual variations, was obtained after a single administration of 800 mg of bacampicillin to 5 healthy volunteers. An adequate antibiotic transfer from the circulation to the bronchial apparatus was demonstrated. Treatment of 34 patients suffering from ampicillin-sensitive bacterial diseases permitted clinical cure of all patients, without onset of side-effects. It is concluded that bacampicillin is preferable to oral ampicillin because of its kinetic and tolerance features.

Adolescent↗
PubMed1981

[Clinical study on a new cephalosporin: CGP 9000 (cefroxadine)].

CGP 9000 (cefroxadine), a new cephalosporine derived from N-acyl-3-alkoxy-7-amino-3-cefem-4-carboxylic acid for exclusively oral use, has been experimented on 67 patients, 41 adults and 20 children. CGP 9000 appeared to possess good therapeutic activity, even in low doses: its rapid absorption and moderate sero-protein bond are a guarantee of an immediate and almost total bioavailability.

Adolescent↗
PubMed1980

[Pharmacokinetics and clinical studies of a new cephalosporin: cefamandole nafate].

The results of a pharmacokinetic and clinical study of cephamandol naphate indicated that the drug quickly reaches high plasma concentration after both i.m. and i.v. bolus administration. Urinary excretion of the biologically active form is as much as 84--90% of the total dose and mostly takes place in the first 6 hr. The therapeutic response was good: clinical cure in 90%, marked improvement in 6.6%, no change in 3.3%.

Adolescent↗
PubMedDate not supplied

The failed back syndrome.

In vertebral surgery we frequently observe patients who complain of lumbar pain at intervals of time which vary after surgery. The causes that may involve the persistence or the recurrence of these symptoms are many, after both decompression surgery, and spinal fusion. In order to favor a more rapid and accurate diagnosis, in our clinical we use a diagnostic algorithm based on the time at which the symptoms occurred. The most modern radiodiagnostic methods allow for a more accurate preoperative diagnosis and a more accurate diagnosis of the pathologies capable of perpetuating or re-accentuating lumbar pain postsurgery.

Algorithms↗