Osteocyte differentiation and the formation of an interconnected cellular network in vitro.

Extracellular matrix (ECM) stiffness and cell density can regulate osteoblast differentiation in two dimensional environments. However, it is not yet known how osteoblast-osteocyte differentiation is regulated within a 3D ECM environment, akin to that existing in vivo. In this study we test the hypothesis that osteocyte differentiation is regulated by a 3D cell environment, ECM stiffness and cell density. We encapsulated MC3T3-E1 pre-osteoblastic cells at varied cell densities (0.25, 1 and 2 × 106 cells/mL) within microbial transglutaminase (mtgase) gelatin hydrogels of low (0.58 kPa) and high (1.47 kPa) matrix stiffnesses. Cellular morphology was characterised from phalloidin-FITC and 4',6-diamidino-2-phenylindole (DAPI) dilactate staining. In particular, the expression of cell dendrites, which are phenotypic of osteocyte differentiation, were identified. Immunofluorescent staining for the osteocytes specific protein DMP-1 was conducted. Biochemical analyses were performed to determine cell number, alkaline phosphatase activity and mineralisation at 2.5 hours, 3, 21 and 56 days. We found that osteocyte differentiation and the formation of an interconnected network between dendritic cells was significantly increased within low stiffness 3D matrices, compared to cells within high stiffness matrices, at high cell densities. Moreover we saw that this network was interconnected, expressed DMP-1 and also connected with osteoblast-like cells at the matrix surface. This study shows for the first time the role of the 3D physical nature of the ECM and cell density for regulating osteocyte differentiation and the formation of the osteocyte network in vitro. Future studies could apply this method to develop 3D tissue engineered constructs with an osteocyte network in place.

[Histological lesions of supraspinatus tendons in full thickness tears of the rotator cuff]. / Les lésions histologiques des tendons des supraspinatus dans les ruptures transfixiantes de la coiffe des rotateurs.

PURPOSE OF THE STUDY: Iterative tears after simple tendon bone suture of transfixiant ruptures of the rotator cuff are frequent. The frequency of iterative ruptures had seemed to be correlated to the importance of the preoperative fatty degenerations of the cuff muscles. But fatty degeneration cannot account for iterative ruptures occurring with no or little preoperative muscle fatty degeneration. The authors have tried to know if iterative ruptures could also be accounted for by the presence on repaired tendinous stumps of histological lesions which are known to lower their mechanical quality, and if such was the case, they have tried to know what could be the impact of these lesions on the repairing technique by suturing cuff ruptures. MATERIAL AND METHOD: Thirty-two distal stumps of ruptured supraspinatus, resected on more than 1 cm to eliminate macroscopic tendinous lesions (thin, lacerated, cleaved, hardened or whitish tendons) and to reach a new stump, slightly bleeding and thick enough to hold the stitches correctly, have been studied on longitudinal histological slides. RESULTS: All the tendinous resected stumps had histological anomalies: dilacerations lesions of the conjunctive tissue, fatty infiltrations, necrosis, scar lesions and micro calcifications were found. The histological lesions were often associated. The histological lesions were an average 4 mm shorter than those of the tendinous resection. In 18 cases however the whole of the resected tendon was histologically abnormal. DISCUSSION: Tendinous histological lesions found on the whole or almost the whole length of the macroscopically abnormal tendinous stumps diminish the mechanical quality of the tendons. Insufficient resection of the tendinous stumps leaving macroscopical lesions and therefore histological lesions could account for iterative ruptures in the first post operative year. Yet complete resection of the macroscopically abnormal tendinous stump does not entail that the neo tendinous stump to be repaired is histologically normal. This encourages to put the stitches well within the zone of the tendinous resection and to bury the tendinous stumps into a highly vascular bony trough. But tendinous resection although logical from the histological and mechanical point of view widens the rupture of the cuff to be repaired. It can make sutures under tension, which can entail iterative ruptures. Musculo-tendinoplasty appears then necessary to perform sutures without tension. CONCLUSION: Histological lesions of tendinous stumps of cuff ruptures correspond roughly to tendinous macroscopic lesions. They could be at the origin of iterative ruptures that take place after simple tendon-bone sutures of ruptured cuffs which are not accounted for by muscular fatty degeneration. They could also partly account for iterative ruptures taking place when pre operative fatty degeneration is evident. It seems logical to resect macroscopically abnormal tendinous stumps before performing a suture. But the tendon-bone suture without tension is then often possible only with musculo-tendinoplasties.

Dialysis arthropathy: outcome after renal transplantation.

PURPOSE: Patients treated by long-term maintenance hemodialysis frequently develop a form of chronic arthropathy that is strongly associated with beta 2-microglobulin amyloid deposition and related, at least in part, to beta 2-microglobulin retention. Successful renal transplantation is followed by a rapid fall in serum beta 2-microglobulin levels and might allow dissolution of amyloid deposits. The purpose of this work was to investigate the effects of renal transplantation on dialysis arthropathy. PATIENTS AND METHODS: Fourteen renal transplant recipients were selected on the basis of previous hemodialysis treatment for at least 10 years (mean 16) and a history of chronic joint pain prior to transplantation. They all received 10 to 17.5 mg/d of prednisone. Posttransplant rheumatologic manifestations were studied prospectively and compared to pretransplant rheumatologic manifestations recorded in medical charts and reported during patient interviews. Pretransplant and posttransplant articular roentgenograms were separately analyzed by three observers who were blinded to timing of the films. Beta 2-microglobulin amyloid was identified by Congo red staining and immunohistology. RESULTS: After a mean posttransplant interval of 54 months (range 12 to 121), the articular condition was improved in 10 patients, unchanged in 1, and worsened in 3, according to patients' assessments. The number of painful joints decreased significantly (P < 0.05) as compared to the pretransplant period. However, the number and size of subchondral bone erosions remained unchanged, destructive arthropathies generally worsened, and articular beta 2-microglobulin amyloid deposits were identified in 2 patients, 2 and 10 years after renal transplantation, respectively. CONCLUSION: Renal transplantation appeared to arrest progression of beta 2-microglobulin amyloid in dialysis patients, but it neither led to dissolution of deposits nor prevented progression of destructive arthropathies. Most articular symptoms were improved, probably as a result of corticosteroid therapy.

Hemodialysis-associated amyloidosis and beta-2 microglobulin. Clinical and immunohistochemical study.

The beta-2 microglobulin type of amyloidosis was identified in articular and para-articular tissues of 14 patients with non-amyloid nephropathies undergoing long-term hemodialysis. Ten patients had carpal tunnel syndrome, 13 had juxta-articular radiolucent cysts (complicated by spontaneous fractures of the femoral neck in three), and six had destructive arthropathies of the large joints of the limbs. Massive amyloid deposits were found in the synovium, capsule, ligaments, articular cartilage, and/or bone. They were characterized by Congo red-induced green birefringence that was sensitive to potassium permanganate treatment. They reacted with anti-beta-2 microglobulin antiserum, whereas they did not react with antibodies directed against AA protein, prealbumin, or immunoglobulins. These data suggest that the potentially disabling arthropathy of hemodialysis is due to amyloid lesions. The persistently elevated plasma beta-2 microglobulin levels may play a role in the pathogenesis of this recently recognized complication, and if so, this complication should be preventable.

Langerhans' cell histiocytosis. Definitive diagnosis with the use of monoclonal antibody O10 on routinely paraffin-embedded samples.

The histological and immunohistochemical findings of 34 biopsy specimens from patients with Langerhans' cell histiocytosis (LCH) are reported, with special emphasis on the findings with CD1a mouse monoclonal antibody (MAb) O10 using paraffin-embedded material. Eighteen patients were treated in an adult hospital (mean age, 26.3 years), and the 16 others were children (mean age, 3 years) from a pediatric center. Specimens included 17 bone, 14 skin, two lung, and one lymph node. Tissue was fixed in formalin or Bouin's, and most bone samples were decalcified in nitric acid. Frozen sections were available for 16 cases and electron microscopy for one. Light microscopy was suggestive of LCH in all cases, characterized by large mononucleated cells with abundant eosinophilic cytoplasm and "coffee bean" nucleus. In 33 of the 34 paraffin-embedded LCH samples, mononucleate cells were stained by MAb O10. As controls, we investigated seven tumors expressing S-100 protein (three nevi, two melanomas, two neurofibromas): all were negative with MAb O10. Five non-Langerhans' cell histiocytoses (three juvenile xanthogranulomas and two Rosai-Dorfman lymphadenopathies) were also negative with MAb O10. The results show that in most cases a definitive diagnosis of LCH can be assessed on paraffin-embedded tissue specimens with the help of immunohistochemistry using MAb O10.

Radiation-induced bone sarcoma following total body irradiation: role of additional radiation on localized areas.

A 44-year-old patient who had had acute monoblastic leukemia developed an osteosarcoma of the pelvic bones 5 years after an allogeneic bone marrow transplant from his HLA-identical sister. He had additionally received superficial cutaneous radiation of the legs and pelvis, over the 3 weeks prior to total body irradiation (TBI), because of cutaneous leukemic lesions. The tumor was a fibrohistiocytomatous osteogenic sarcoma. The first lesion was in the right ilium, and a second lesion appeared 18 months later, symmetrically on the left ilium. Despite treatment, the patient died from metastases. At the time of diagnosis of radiation-induced sarcoma, the patient was free of leukemia and had several risk factors already reported to favor the development of solid tumors in stem cell recipients. These include acute leukemia, TBI and graft-versus-host disease. As he developed symmetrical lesions of the pelvic bone, and because of the histology of the radiation-induced tumor, we assumed that the additional radiation of the skin prior to TBI may have contributed to the pathogenesis of this malignant fibrous histiocytoma. Therefore, the risk/benefit ratio should be carefully considered in unusual indications. These patients should benefit from a close follow-up of the superimposed areas.

A case of destructive polyarthropathy in a 17-year-old youth following pefloxacin treatment.

Joint and muscle pain have been reported with quinolones; however, arthropathies induced by quinolones do not result in erosive changes in humans, although such changes have occurred in animal studies. We report an unusual case of destructive polyarthropathy in a 17-year-old boy after treatment with pefloxacin 800 mg/day for 3 months. Pefloxacin may have accentuated the cartilage damage in this case, even if an underlying joint disease could not be excluded.

Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1: a clinicopathologic and molecular study of 17 patients.

OBJECTIVE: To identify potential prognostic factors and criteria for early detection of malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1 (NF1). DESIGN: Retrospective study of malignant peripheral nerve sheath tumors in a cohort of 395 patients with NF1 followed up between October 1, 1988, and January 1, 1999; review of the clinical and histological characteristics of treatment and course; and analysis of p53 mutations and overexpression in tumors. SETTING: Teaching hospital referral neurofibromatosis center for adults. PATIENTS: Seventeen patients with NF1 (9 males and 8 females). Mean +/- SD patient age at diagnosis was 32 +/- 14 years. MAIN OUTCOME MEASURES: (1) Clinical symptoms, (2) comparison of p53 mutations and overexpression in benign vs malignant tumors; and (3) median survival. RESULTS: Twelve patients had high-grade tumors. All tumors except 1 developed on preexisting nodular or plexiform neurofibromas. Pain and enlarging mass were the first and predominant signs. None of the benign tumors displayed significant p53 staining or p53 mutations. Six of 12 malignant tumors significantly overexpressed p53, and 4 of 6 harbored p53 missense mutations. Median survival was 18 months overall, 53 months in peripheral locations, and 21 months in axial locations. CONCLUSIONS: Malignant peripheral nerve sheath tumors are highly aggressive in NF1. They mostly arise from plexiform or nodular neurofibromas. Investigations and deep biopsy of painful and enlarging nodular or plexiform neurofibromas should be considered in patients with NF1. Late appearance of p53 mutations and overexpression precludes their use as predictive markers of malignant transformation.

Study on static morphometric parameters for a diagnostic approach of osteoporosis.

The diagnostic value of the morphometric parameters Vv,Sv, dtrab of cancellous bone and relations between them were examined. Iliac bone biopsies of osteoporotic and spasmophilic subjects were studied by means of a Mop 1 semi automatic digitizer tablet joint to a C B M 3032 microprocessor. Both the average Sv and Vv values were significantly different between the two groups. Concordance of Sv values with the radiological diagnosis was closer than Vv ones. The global estimation of mean trabecular thickness is discussed. In conclusion the confrontation of experimental data shows that simple global measure of Sv completes and precise the knowledge of skeleton state.

Poor eight-year survival of cemented zirconia-polyethylene total hip replacements.

Between January 1988 and January 1991 we performed 100 consecutive cemented total hip replacements using a zirconia head, a titanium alloy stem and a polyethylene cup. We reviewed 78 of these hips in 61 patients in detail at a mean of 5.8 years (1 to 9). Aseptic loosening was seen in 11 hips (14%). Eight needed revision. In total, 37 cups (47.5%) showed radiolucent lines, all at the cement-bone interface, with 18 (23%) involving all the interface. Of the 78 femoral implants, 17 (21.7%) showed radiolucent lines, and two, which had a complete line of more than 1 mm thick, definite endocortical osteolyses. There was also an abnormally high incidence of osteolysis of more than 2 mm at the calcar. Survivorship analysis showed that only 63% were in situ at eight years. These worrying results led us to abandon the use of zirconia heads, since at the same hospital, using the same femoral stem, cement and polyethylene cup, but with alumina femoral heads, the survival rate was 93% at nine years. We discuss the possible reasons for the poor performance of zirconia ceramic.

Methotrexate diffusion from acrylic cement. Local chemotherapy for bone tumours.

We investigated the possible use of acrylic cement containing chemotherapeutic drugs in the treatment of malignant lesions in bone. The diffusion of methotrexate (MTX) from methylpolymethacrylate implants was studied in vitro: polymerisation of the cement did not destroy the drug; liberation began immediately and about 10% was released by 18 hours. Some release continued for as long as six months. In vivo experiments on rats with induced osteosarcoma showed that MTX in cement had both local and general effects which were dependent on the dosage. A series of 17 large dogs with spontaneous osteosarcoma were then treated by local resection and cement containing MTX. General chemotherapeutic effects were detectable from 2 hours to 5 days, survival was increased and local recurrence was reduced, but there were four cases of delayed wound healing. Preliminary studies in human patients confirm the possibility that this method of local chemotherapy could be a useful addition to the treatment of malignant tumours of bone.

Prognostic factors in patients with localized Ewing's sarcoma: the effect on survival of actual received drug dose intensity and of histologic response to induction therapy.

To bring to the fore the most important prognostic factors in Ewing's sarcoma (ES) with current protocols, we studied the classical prognostic factors, dose intensity (DI) of actual received drugs, age and histological response to induction therapy and their correlation in 39 patients with localized ES treated from 11/85 to 06/95 to identify eventual predictors of event-free survival (EFS). Inclusion criteria were age 35 yr or less, definitive local treatment by our team and chemotherapy including at least 4 drugs: vincristine (VCR), dactinomycin (DACT), doxorubicin (DOXO) cyclophosphamide (CPX). The endpoint was the absence of relapse. Parameters related to the status of patients were tested using the Chi square test or Fisher's exact test. The non parametric Kruskal-Wallis test was used for quantitative data. When necessary stratified analysis was done using the Mantel Cox test. With a median follow-up of 7 yr, overall survival (OS) and EFS were both 67% at 7 yr. According to univariate analysis, the significant predictors of survival were the DI of VCR and DACT, the histological response to preoperative chemotherapy (CT), the patient's age (< 18 yr DFS: 84%; > 18 yr DFS: 38%). The risk of metastases was almost tenfold higher in patients with low received DI of VCR (DFS 40% versus 95%) and of DACT (DFS 48% versus 94%). The prognostic value of primary tumor characteristics (tumoral volume or location) was erased by the comprehensive treatment. Following multivariate analysis, the actual received DI of VCR (p < 0.02) and DACT (p < 0.03) and the histological response to preoperative CT (p < 0.05) were retained as the only significant independent predictors of EFS. Taking into account the actual received DI of VCR and DACT, the prognostic value of age disappears. In conclusion, this study points out the main role of the drug DI in ES (particularly VCR and DACT) and of histological response to preoperative CT.

Iliac vein thrombosis complicating SAPHO syndrome: MRI and histologic features of soft tissue lesions.

Subclavian and superior vena cava obstruction complicating SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis) syndrome has been described. We report the first case to our knowledge of iliac vein thrombosis complicating lumbar vertebral osteitis due to SAPHO syndrome. Lumbar MRI demonstrated a large tissue mass anterior to the involved vertebras and surrounding the right iliac vein. Histology of the mass showed aseptic inflammation.

Imaging of chordomas of the mobile spine.

In this retrospective study twelve histologically confirmed cases of spinal chordoma have been reviewed. Plain radiographs were performed in all cases, and CT scans in 11 patients. Four patients had post-myelography CT. Five patients were explored by MRI, and two had a post-DOTA-gadolinium MR study. Ten patients underwent spinal arteriography. Cervical spine chordomas (3 cases) were osteolytic, developed laterally to the vertebral body and involved one of more adjacent vertebrae. Thoracic and lumbar chordomas (9 cases) were usually centrally located in the vertebral body with no adjacent involvement and presented as osteo-sclerotic or mixed osteolytic-osteosclerotic lesions. CT scans provide a good view of the extravertebral component of the tumour, but MRI is the best imaging method to evaluate tumoral extension. Intravenous gadolinium injection seems to produce a better delineation of the epidural extent of the tumour at cervical level. Angiography remains useful for presurgical evaluation.

CT-guided vertebral biopsy. A report of 89 cases.

The authors report the results of 89 vertebral biopsies performed under CT guidance, classified according to the type of pathology and the site of the lesion. A correct diagnosis was obtained in 89 cases. No complication was observed. The value of CT guidance in vertebral biopsy is emphasized.

[Solitary infantile myofibromatosis of bone]. / Myofibromatose infantile osseuse isolée.

We report one case of Solitary infantile Myofibromatosis of Bone in a 14-year old girl. Radiologic features of the tibial lesion were consistent with the diagnosis of a benign bone tumor. The final diagnosis was made on a total resection of the tumor. Histologically, the tumor consisted of nodules, hyalinized or cellular, with spindle-shaped cells resembling fibroblasts or smooth-muscle cells. There were numerous vascular spaces in close contact with these nodules. The tumor cells were immunoreactive with anti-alpha-smooth muscle actin antibodies. These data were consistent with the diagnosis of Myofibromatosis. The histologic features were similar to those of Infantile Myofibromatosis of other sites such as skin and soft tissue. The case reported is rare and not yet published, due to the age and sex of the patient, and the location of the tumor.

[Mediastinal parathyroid adenoma. Localization by scintigraphy with methoxy-isobutylisonitrile]. / Adénome parathyroïdien médiastinal. Localisation par scintigraphie au méthoxy-isobutyl isonitrile.

Cases of inaccessible mediastinal parthyroid adenomas are rare (1% of parathyroid tumours). Previously, when the localization had been confirmed by imaging techniques, we performed exploratory cervicotomy, followed by sternotomy after explorations had been completed. This procedure required two operations and sternotomy sometimes gave blank results. We therefore prospectively evaluated technitium-99m labelled methoxy-isobutyl isonitrile scintigraphy to localize an adenoma in the anterior mediastinum. A 39-year-old patient was hospitalized for primary hyperparathyroidism which had caused nephrocalcinosis and decalcification. Serum calcium was 130 g/L and phosphorus 16 mg/L. Cervical echography, thallium scintigraphy and computed tomography were negative. Scintigraphy with technitium-99m labelled methoxy-isobutyl isonitrile visualized a tumoural formation in the upper mediastinum near the ascending aorta. Magnetic resonance imaging centered on this zone revealed a 13 x 8 mm formation. Cervicosternotomy was performed initially. A 280 mg parathyroid adenoma was removed. The three other parathyroid glands were found to be normal. Follow-up was uneventful and the serum levels of calcium and phosphorus rapidly returned to normal. This preliminary case has demonstrated that methoxy-isobutyl-isonitrile scintigraphy can be an effective first intention exploration for primary hyperparathyroidism. Further results should indicate its sensitivity and specificity.

[Magnetic resonance imaging in the evaluation of a pseudotumoral form of villonodular synovitis of the knee. A case report]. / Apport de l'imagerie par résonance magnétique dans le bilan de la synovite villonodulaire du genou à forme pseudo-tumorale. A propos d'un cas.

The use of magnetic resonance imaging was investigated by the authors after having observed one case of pseudo tumoral villonodular synovitis of the knee. Its fiability was compared with those of computerised tomography, arteriography and arthrography.

[Cytologic study of giant cell tumors. Electron microscopy. Cyto-enzymology]. / Etude cytologique de la tumeur à cellules géantes. Microscopie électronique. Cyto-enzymologie

A cyto-enzymologic study of giant cells tumor revealed a high acid phosphatase activity in multi-nuclear cells (as in osteoclasts) and a very low alcaline phosphatase and peroxydase activity. Acid phosphatase was located in lysosom which were concentrated in definite cytoplasmic areas. The blood rate of this enzyme should be raised if it were excreted by the cells. Therefore a study of acid phosphatase blood rate could reinforce a diagnosis based on X-rays and a raising rate after surgery could help for early detection of recurrences.

[Pigmented nodular tenosynovitis. A misdiagnosed etiology of isolated tumefaction of fingers or toes]. / Ténosynovite nodulaire hémopigmentée. Une étiologie méconnue de tuméfaction isolée des doigts et des orteils.

BACKGROUND: Pigmented nodular tenosynovitis (more commonly called giant cell tumor) is a benign tumor of synovial joint or tendon sheaths. CASE REPORT: A 17-year-old girl had a tumefaction of the first toe. The mass was firm and painless and had been present for one year. Radiological studies revealed a cystic area of the first phalanx. Magnetic resonance imaging demonstrated a poorly vascularized tissular lesion. Surgical excision of the tumor was performed. Macroscopic and histologic findings confirmed the diagnosis of pigmented nodular tenosynovitis. DISCUSSION: Clinical and radiological aspects of nodular tenosynovitis are characteristic. This diagnosis should be made by dermatologists. Eighty percent of cases occur in fingers and more rarely in toes. Patients are usually females (60 p. 100). A subcutaneous mass is the most common presenting sign whereas pain or joint swelling are rare. Optimal treatment is surgical resection. The only risk is recurrence (20 p. 100).