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Biomedical subjects

N Passuti

Publications and source records attributed to N Passuti.

At least 37 records · Page 2Linked to original sources
PubMed1999

Osteogenic potential in vitro of human bone marrow cells cultured on macroporous biphasic calcium phosphate ceramic.

Calcium phosphate ceramics are synthetic bone substitutes that promote bone formation by osteoconduction. However, they have shown an osteogenic potential in vivo in animal models when associated with bone marrow cells. In order to develop an osteogenic human "hybrid material," we studied the in vitro osteogenic potential of human bone marrow cells cultured on macroporous biphasic calcium phosphate (BCP) pellets in the presence of dexamethasone with or without 1alpha,25 dihydroxyvitamin D3. We were examining, in particular, their mesenchymal stem cell proliferation and hematopoietic potential. Osteogenic differentiation was evaluated in terms of alkaline phosphatase activity and immunological characterization of the extracellular matrix formed by these cells. The specimens were observed by scanning and transmission electron microscopy. Human mesenchymal stem cells proliferated on macroporous BCP ceramic, with a doubling time delayed at the beginning of the culture as compared to the cultures realized on plastic. These cells maintained a hematopoietic activity identical to that of cultures performed in plastic wells. The proliferating mesenchymal stem cells expressed an osteoblastic phenotype, as shown by alkaline phosphatase activity and the synthesis in ceramic macropores of an extracellular matrix composed of fibronectin, osteocalcin, and collagen I (but not collagen III). In addition, numerous microcrystals of apatite precipitated on the extracellular matrix, producing a mineralized fibrillar network within the ceramic not observed with cell cultures realized on plastic. These results demonstrate that human mesenchymal stem cells cultured on macroporous BCP ceramic express and conserve their osteoblastic phenotype even after one month of culture and that these osteogenic cells are able to form new bone matrix in a BCP ceramic in vitro.

Biocompatible Materials↗
PubMed1999

Expression of leukemia inhibitory factor by cartilage-forming tumors of bone: an immunohistochemical study.

Recent studies have implicated leukemia inhibitory factor in connective-tissue metabolism involving the remodeling of bone and the destruction of cartilage tissue. This cytokine, which has also been implicated in the proliferation of solid tumor, is expressed by osteotropic tumor cell lines. The present study investigated the presence of leukemia inhibitory factor in cartilage tissue harvested from cartilage-forming bone tumors. Immunohistochemical study showed that it was present in all benign enchondromas (n = 8) and malignant chondrosarcomas (n = 6) but not in control tissue (n = 3). The cytokine was localized in only cytoplasmic areas of cartilage cells. The number of stained cells ranged from less than 5% in enchondroma of the hand to more than 70% in grade-III chondrosarcoma. Moreover, high levels of leukemia inhibitory factor were found in the primary culture of tumor tissues (n = 7). These results question the significance of leukemia inhibitory factor in tumor-associated bone resorption and the potential role of this cytokine as a prognostic marker.

Adolescent↗
PubMed1999

Presence of leukaemia inhibitory factor (LIF) and LIF-receptor chain (gp190) in osteoclast-like cells cultured from human giant cell tumour of bone. Ultrastructural distribution.

The behaviour of multinucleated giant cells (MNC) obtained from a giant cell tumour of the tibia and cultured on glass coverslips or on devitalized dentin slices was investigated using light and electron microscopy. Cells were studied in the presence or absence of LIF a cytokine known to be involved in bone turnover and to act as a growth factor in some solid tumours. The direct effect of LIF on MNC was examined by a post-embedding colloidal gold immunocytochemistry process using human anti-LIF and anti-LIF-receptor (chain gp190) antibodies. After 7 days of culture, the MNC obtained displayed osteoclast immunocytochemical features. Moreover, these MNC were able to resorb large amounts of dentin and presented typical features of active osteoclasts. Immunolocalization of LIF and LIF-receptor revealed the presence of this cytokine and its receptor within the cytoplasm and nucleus of active resorbing MNC. LIF upmodulated MNC number and nucleation but decreased their ability to resorb dentin. The present study suggests that MNC obtained from human GCT, currently considered as osteoclast-like cells, are targets for LIF and may be a source of LIF production in this pathological condition.

Bone Neoplasms↗
PubMed1999

Influence of a cellulosic ether carrier on the structure of biphasic calcium phosphate ceramic particles in an injectable composite material.

An injectable composite material based on biphasic calcium phosphate (BCP) and a nonionic cellulose ether has been elaborated for use in percutaneous surgery for spine fusion. This paper reports the characterization results of this material by spectroscopic techniques including X-ray diffraction (XRD), infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) fitted with an energy dispersive X-Ray analysis system and high-resolution transmission electron microscopy (HR-TEM). From FTIR and XPS results, it was observed that the adhesion between the polymer and the ceramic might be insured by oxygen bridging developed through an ionic bonding between calcium ions and (C-O) groups of the polymer. Moreover, XPS showed attraction of Ca2+ ions in the polymer matrix, while the ceramic surface was modified in a HPO4(2-) -rich layer. These results suggest a possible dissolution/precipitation process at the interface ceramic/polymer. HR-TEM observations supported this hypothesis, showing a light contrasted fringe at the surface of the ceramic grains in the composite paste. As well, changes in the XRD spectra could indicate a small decrease in the crystal size of the BCP powder through the contact to polymer solution. In addition, SEM observation showed a decrease of the initial BCP granulometry. Aggregates of 80-200 microm seemed to be mostly dissociated in micrograins. The ceramic grains were coated with and bonded between each other by the polymer matrix, which acted as spacer in between the ceramic grains, creating a macroporous-like material structure.

Biocompatible Materials↗
PubMed1999

[Physiopathology of tumor-induced osteolysis].

Osteolysis, the most common expression of bone tumor, can cause pain, pathological fracture, epidural spinal cord compression and hypercalcemia. Multinucleated osteoclast-like cells, the main agents in bone resorption, are numerous in benign giant cell tumor of bone and can be recruited and activated by various carcinoma cell lines in vitro in animal models. Polykarion macrophages are also able to resorb bone matrix in a favourable tumoral environment. Direct bone resorption by tumor cells has recently been described in vitro and in vivo in animals. The presence of diffusible substances such as hormones, cytokines and growth factors creates a favourable microenvironment for stimulation of osteoclast-like cells and polykarion macrophages functional ability to resorb bone matrix. These mediators act within a complex but still unelucidated network involving high cell production (tumor cells, normal and reactional stroma as well as hematopoietic cells) and many targets (tumor production (tumor cells, normal and reactional stroma as well as hematopoietic cells) and many targets (tumor cells, monocyte/macrophage lineage cells, and osteoclast-like cells). The presence in the same environment of all these stimulating factors for tumor cell growth and resorbing ability could explain the vicious circle of tumoral and osteolytic progression. A better understanding of the complex mechanism of tumor induced osteolysis is essential for improving the conventional surgical approach to this pathology.

Animals↗
PubMed1999

[Neurologic complications of surgical treatments].

Neurological complications during correction of scoliosis remain a rare but very severe event. Prevention by analysis of risk factors pre-operatively and assessment of complications per-operatively could be done using wake-up test and evoked potential monitoring, to emphasize short term prevention of these complications. A clear information must be given to the patient and his family before such an operation.

Humans↗
PubMed1998

Long-term bone response to particulate injectable ceramic.

Biphasic calcium phosphate particles (BCP), alone or combined with a cellulosic ether vehicle in an injectable composite material (COMP), were implanted in femurs of rabbits. The long-term follow-up (up to 78 weeks) indicated: (1) BCP and COMP induced a foreign-body inflammatory reaction but without fibrous encapsulation. Phagocytosis was mediated by mononucleated macrophages (MC) and giant multinucleated cells (GMNC). Phagocytosis was stronger with COMP and required the recruitment of GMNC while it primarily involved MC in the case of BCP. (2) There appeared to be no significant difference between the bone ingrowth in the defects packed with BCP (dBCP) and in those filled with COMP (dCOMP). Bone reconstruction mostly was achieved after 4 weeks in dBCP but took more time to reach the center of dCOMP. High bone remodeling was observed at the last evaluation times, especially in the case of COMP. (3) Degradation of the materials occurred mainly during the first 4 weeks and was more severe for COMP, which probably was related to the smaller granulometry of its mineral phase. Cell-mediated degradation went on for the 78 weeks and followed two processes: phagocytosis and/or extracellular dissolution of the calcium phosphate particles.

Animals↗
PubMed1998

Increased levels of leukaemia inhibitory factor (LIF) in urine and tissue culture supernatant from human primary bone tumours.

Fifty-five adult patients with primary bone tumour, 27 benign and 28 malignant tumours, were assayed for leukaemia inhibitory factor (LIF) in urine and serum samples. Supernatant was obtained from primary tumour tissue cultures in 24 cases (14 benign, 10 malignant tumours). LIF was found in 11 urine samples (16.7%, 1 benign and 10 malignant tumours). In 23 urine samples from patients with malignant bone tumour tested before any treatment, LIF was detectable in eight cases (34.7%). High LIF levels were found in all supernatants from malignant tumour cultures and in supernatant from 12 of the 14 benign tumours cultured. LIF was never detected in control urine samples or supernatants from normal cancelous bone cultures. These first in vivo data concerning LIF in primary bone tumours raise the question as to the cellular origin of this multifunctional cytokine and its potential role in solid bone tumours and bone tumour resorption.

Adolescent↗
PubMed1998

Cytokines, growth factors and osteoclasts.

Osteoclasts, the main protagonists involved in bone resorption mechanisms, are generally considered to be of haematopoietic origin, although the exact nature of the primary osteoclastic stem cells is still unknown. In vitro cellular models developed to study the different events of osteoclastic differentiation have revealed that not only several cell types (osteoblasts, monocytes, lymphocytes, etc.) but also many soluble factors (cytokines, hormones, vitamins, ions, etc.) and extracellular matrix elements (osteopontin, osteocalcin, etc.) are involved in osteoclastic differentiation and activation. This article provides an exhaustive review of recent knowledge on the origin of the osteoclast and the main substances involved in the osteoclastogenesis and activation of these cells.

Animals↗
PubMed1998

Usefulness of neurogenic motor evoked potentials for spinal cord monitoring: findings in 112 consecutive patients undergoing surgery for spinal deformity.

Neurogenic motor evoked potential (NMEP) monitoring, which basically represents a monitoring of both motor and somatosensory tracts, has been proposed as a warning system in preventing neural damage during spinal surgery. The aim of this study was to report our clinical experience in 112 consecutive patients undergoing surgery for spinal deformity, and to emphasize the interest of NMEP monitoring. NMEPs were elicited in each patient by electrical stimulation of the spinal cord via needle electrodes placed by the surgeon in the rostral part of the surgical field, and recorded from the right and left sciatic nerves. Concomitantly, somatosensory evoked potentials (SSEPs) were obtained using a standard method. No false-negative cases of intra-operative spinal cord damage were reported. In 3 patients, both NMEPs and SSEPs suddenly disappeared during specific surgical manipulations of the vertebral implants. In these patients, the level of the lesion was easily recognized by moving the stimulating electrodes of NMEPs along the spinal cord, allowing the surgeon to perform laminectomy at the appropriate vertebral level. Spinal cord decompression was a success in two patients, the last unfortunately being paraplegic. Two additional patients exhibited transient reduction in NMEP amplitude at the insertion of a rod while SSEPs did not change significantly. In these two cases, the surgeon modified his procedure according to the NMEP changes, possibly avoiding a neurological complication. Each time evoked potentials were significantly altered, significant information was more rapidly acquired with NMEPs than with SSEPs. These results suggest that NMEPs can be used as primary choice for detecting impeding lesion of the spinal cord during critical steps of spinal surgery.

Adolescent↗
PubMed1998

Synthetic porous ceramic compared with autograft in scoliosis surgery. A prospective, randomized study of 341 patients.

We have evaluated the use of a synthetic porous ceramic (Triosite) as a substitute for bone graft in posterior spinal fusion for idiopathic scoliosis. In a prospective, randomised study 341 patients at five hospitals in the UK and France were randomly allocated either to autograft from the iliac crest or rib segments (171) or to receive Triosite blocks (170). All patients were assessed after operation and at 3, 6, 12 and 18 months. The two groups were similar with regard to all demographic and baseline variables, but the 184 treated in France (54%) had Cotrel-Dubouset instrumentation and the 157 treated in the UK usually had Harrington-Luque implants. In the Triosite group the average Cobb angle of the upper curve was 56 degrees, corrected to 24 degrees (57%). At 18 months, the average was 26 degrees (3% loss). In the autograft group the average preoperative upper curve of 53 degrees was corrected to 21 degrees (60%). At 18 months the mean curve was 25 degrees (8% loss). Pain levels after operation were similar in the two groups, being mild in most cases. In the Triosite group only three patients had problems of wound healing, but in the autograft group, 14 patients had delayed healing, infection or haematoma in the spinal wound. In addition, 15 autograft patients had pain at the donor site at three months. Seven had infections, two had haematoma and four had delayed healing. The haematological and serum biochemistry results showed no abnormal trends and no significant differences between the groups. There were no adverse events related to the graft material and no evidence of allergenicity. Our results suggest that Triosite synthetic porous ceramic is a safe and effective substitute for autograft in these patients. Histological findings on biopsy indicate that Triosite provides a favourable scaffolding for the formation of new bone and is gradually incorporated into the fusion mass.

Adolescent↗
PubMed1998

Heterotopic implantation of mouse bone-marrow cells: an in vivo model allowing analysis of mineral phases during mineralization processes.

Heterotopic calcification induced after implantation of bone-marrow cells under the murine kidney capsule was used to study the mineral phases occurring during the mineralization process. Ossicles were found to contain numerous osteoblastic cells that produced an organic matrix closely associated with active hematopoietic tissue. During implantation of bone marrow, needle-shaped microcrystals were progressively deposited on collagen fibers. The mineral formed in the heterotopic calcification consisted mainly of calcium phosphate. The distribution and density of the microcrystals were heterogeneous after 6 weeks of implantation but became homogeneous and well-crystallized after 10 weeks. The Fourier transform infrared microspectroscopy provided important spatial data on the nature of the mineral formed and the changes in the mineral environment. Similarities were noted between young bone (bone callus) and 6-week heterotopic ossicles, and between adult bone and 10- or 12-week heterotopic ossicles. The study demonstrated that murine heterotopic calcification under the renal capsule can be a very useful model for studying bone apatite formation during the mineralization process.

Animals↗
PubMed1998

[Combined tibio-talar and subtalar arthrodesis by retrograde nail in hindfoot rheumatoid arthritis].

PURPOSE OF THE STUDY: Many techniques for ankle arthrodesis have been described. Some are not applicable to patients with severe rheumatoid arthritis (RA) because of osteopenia and deformities. This study describes a new surgical technique for arthrodesis in painful valgus deformity of the hind-foot in advanced rheumatoid arthritis (RA) with severe osteopenia. MATERIALS: The present series included 9 patients. Eleven talocrural and talocalcaneal arthrodeses were performed for degenerative changes secondary to RA involving hind-foot joints. All patients were reviewed after an average follow-up of 6 years. Mean duration of RA was 34 years. All patients had severe osteopenia, including major deformations of the hind-foot in 5 cases. METHODS: After removal of talocrural and talocalcaneal articular surfaces using an anterolateral approach, deformities were corrected by removal of an appropriate bone wedge. A Küntscher nail was then positioned in the calcaneal plantar cortical through the plantar surface of the foot and driven proximally into the medullary canal of the tibia through the talus. This nail allowed both deformity correction and fixation. Aftercare required immobilization in a short leg cast. Weight bearing was allowed with the cast approximately 5 weeks after surgery. The ankle was immobilized for 7.5 weeks. DISCUSSION: Results showed a 80 per cent fusion rate. Two non-unions occurred (one recurrence of valgus deformity after early nail migration requiring removal of the nail; and the other asymptomatic). A complication occurred in one foot (delayed healing). At follow-up, all patients but one were satisfied with respect to pain relief and residual deformities. Our results are comparable with those of other series and should be considered in the context of severe RA. CONCLUSION: This technique of vertical retrograde transarticular nailing allows an easy control of hind-foot deformities correction. Other techniques are preferable in case of solid bone. This technique is an acceptable alternative in advanced RA.

Adult↗
PubMed1997

Interpretation and utility of traction radiography in scoliosis surgery. Analysis of patients treated with Cotrel-Dubousset instrumentation.

STUDY DESIGN: An analysis of a standardized method of traction radiography for the evaluation of reducibility of scoliosis. OBJECTIVES: To determine whether and how preoperative fraction radiography can provide objective information and to compare traction radiography with supine side-bending radiography. SUMMARY OF BACKGROUND DATA: Flexibility of scoliosis deformity remains an arbitrary concept. No objective method of preoperative evaluation of reducibility has been established. METHODS: The utility of a standardized method of traction radiography was evaluated in 74 patients with idiopathic scoliosis who were aged 14-22 years and treated with Cotrel-Dubousset instrumentation. RESULTS: In thoracic curves, the postoperative Cobb angle was highly correlated with the preoperative Cobb angle in traction (r = 0.82). However, such correlation was much lower with lumbar curves (r = 0.54). The reducibility of the thoracic curve by traction as expressed by the ratio to the original curve was dependent on the magnitude of the original curve (P = 0.005), and this parameter proved less informative than the absolute angle values. Time-related analysis of 30 patients who were observed for more than 5 years revealed that the high correlation between the preoperative angle of thoracic curves in traction and their postoperative angle decreased with the follow-up time (r = 0.80-0.65). A comparison of traction radiography and supine side-bending radiography showed that these two tests were practically equivalent in terms of evaluating the reducibility of curves. CONCLUSION: The results provide an objective interpretation of traction radiographs for scoliosis.

Adolescent↗
PubMed1997

Influence of local environment on incorporation of ceramic for lumbar fusion. Comparison of laminar and intertransverse sites in a canine model.

OBJECTIVES: To evaluate bone growth into macroporous ceramic in a canine model in terms of the effect at the lumbar spine site (lamina versus transverse process site) and the depth of the area within the ceramic block (peripheral or central areas). SUMMARY OF BACKGROUND DATA: Previous comparative studies have assessed that the efficacy of bone graft substitutes for spine fusion depends on their physicochemical properties and on the mechanical environment, but rarely on the grafting site at the lumbar spine level. METHODS: Posterior and lateral arthrodesis using pedicular instrumentation was performed at L2, L3, and L4 with a parallelepipedic ceramic block in an experimental group of dogs. A second group of dogs was fused with only autogenous bone graft to compare the fusion stiffness obtained with this material with the stiffness obtained with ceramic. Dogs were studied for 9 months. A biomechanical test and histomorphometric analysis were conducted. RESULTS: With the biomechanical test, no significant differences were found between ceramic and autogenous bone. The percentage of newly formed bone was higher (P < 0.0001) at the lamina (26.52 +/- 6.45%) than at the transverse process site (17.33 +/- 2.54%). For both locations, the highest amount of newly formed bone was observed in the area of close contact between ceramic and bone, and the lowest was observed in central areas (24.6 +/- 5.9% for the laminar site, 14.79 +/- 1.75% for the transverse process site). CONCLUSION: This animal study, which replicated the human procedure in posterolateral lumbar fusion, showed a significant difference of ceramic incorporation between laminar and intertransverse sites. This histomorphometric analysis also confirmed the relationship between bone in-growth and ceramic thickness and ceramic contact area with bone.

Animals↗
PubMed1997

Changes in the unfused lumbar spine in patients with idiopathic scoliosis. A 5- to 9-year assessment after cotrel-dubousset instrumentation.

STUDY DESIGN: Postoperative changes in the lumbar spine were studied retrospectively in patients with adolescent idiopathic scoliosis who had been treated with Cotrel-Dubousset instrumentation. OBJECTIVE: To examine middle-term changes in the unfused lumbar segments below an instrumented scoliosis fusion. SUMMARY OF BACKGROUND DATA: Scoliosis fusion by the Harrington method is known to be associated with a flat back in the fused area and subsequent degenerative changes in the segments below the fusion. No data have yet been published concerning a segmental instrumentation system. PATIENTS AND METHODS: Thirty patients with idiopathic scoliosis, between the ages of 14 and 22 years at the time of surgery, were observed for 5-9 years after surgery. Activity, pain, complications, and 21 radiographic parameters were assessed. RESULTS: The prevalence of low back pain increased from 3% before surgery to 20% at the final follow-up visit, although in none of the patients was the pain so severe that specific treatment was required. Radiographically, uninstrumented lumbar segments generally were realigned successfully in the frontal plane. Analyses in the sagittal plane revealed tendencies to a gradual increase in lumbar lordosis, anterior-upward tilting of the lowest instrumented vertebra, and posterior shift of the sagittal spinal balance. During the follow-up period, seven patients (23%) developed degenerative changes, including mild junctional kyphosis, retrolisthesis, narrowing of disc spaces, or osteophytes. CONCLUSION: Whereas the overall clinical and radiographic results of surgery were satisfactory, the unfused lumbar segments required careful surveillance, especially in the sagittal plane.

Activities of Daily Living↗
PubMed1997

Ovine anterior cruciate ligament reconstruction using a synthetic prosthesis and a collagen inductor.

The evaluation of composite anterior cruciate ligament prostheses, the union of an inductor of collagen and a synthetic fibre, are described. They were implanted in 10 sheep models for six months. None of the ligaments were broken, and the dynamic radiography was stable during this time. After harvesting them, a histologic study was performed on the intra-osseou and intra-articular portion, and on the synovial tissue. Biocompatibility was excellent. An osseous anchorage was found in 50% of cases and a fibrous ingrowth with well oriented fibres in each case. The results of this study show that the matrix has only partially played its role, because there was no improvement of fibrous ingrowth compared with other studies. However this fact corresponds to results at only 6 months and it is necessary to identify the type of collagen.

Journal Article↗