[A serious and unexpected infectious complication after transrectal prostate biopsy]. / Une complication infectieuse grave inattendue après biopsie transrectale de prostate.

Serious infectious complications may appear after a surgical procedure despite antimicrobial prophylaxis. We report a case of Escherichia Coli meningitis after a prostate puncture biopsy. Many factors may have contributed to this rare complication such as fluoroquinolone resistance, and/or the bacterium's ability to cross the brain blood barrier. The patient was not found susceptible to severe infections.

Role of fibronectin during biological apatite crystal nucleation: ultrastructural characterization.

The role of adhesion molecules like osteopontin and bone sialoprotein, both containing the Arg-Gly-Asp sequence have been shown to have a role in mineral formation, whereas fibronectin (FN), another adhesive protein, was never studied during the mineralization processes. The formation and maturation of biological apatite crystals are under matrix control, and one of the roles of specific crystal proteins is to control the nucleation and growth of biological apatite during the mineralization process (promotion or inhibition). In the case of calcium phosphate ceramic used as a bone substitute, a dissolution-precipitation process occurs after implantation before the bone ingrowth and bone mineralization. The early precipitation consists of common biological apatite crystals. These crystals are the result of secondary nucleation and a heteroepitaxic growth process on synthetic residual crystals. In in vivo studies, hydroxyapatite crystals were implanted subcutaneously into mice for 1 or 2 weeks. Fibronectin immunogold labeling of the newly formed crystals on surfaces of high-resolution transmission electron microscopy sections of retrieved implants revealed the close association of these precipitated crystals with FN. In in vitro experiments using a solution of human FN incubated in the presence of calcium phosphate crystals, we obtained apatite crystal precipitation. The fibronectin network observed in high-resolution transmission electron microscopy showed numerous clusters of very small particles (1 nm in diameter and 2 nm in length), whereas the same experiment realized as control on albumin revealed no crystal precipitation. These results demonstrate for the first time the role of FN in early biological crystal nucleation. This process could have important biological significance in accounting for ectopic calcification, primary nucleation in calcified tissue, and bone ingrowth on calcium phosphate ceramics.

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.

Ultrastructural and electron diffraction of the bone-ceramic interfacial zone in coral and biphasic CaP implants.

We investigated the influence of natural coral implants used as a bone substitute on the quality of bone ingrowth in rabbits 2, 3, and 6 weeks after implantation. Explants were characterized by transmission electron microscopy and electron diffraction. Bone ingrowth has been previously demonstrated by light microscopy, however, few have been performed in electron microscopy to compare mineralized tissue ingrowth in coral implants which occurs at the expense of calcium carbonate to that of calcium phosphate (CaP) implants. The interface between coral aragonite and mineralized tissue or bone was abrupt, with no invasion of the aragonite structure by newly formed crystals, as occurs in micropores when biphasic CaP (BCP) ceramics were used. The restoring process appears to be different from that induced by BCP implants. Precipitation of needle-like apatite crystals on the CaCO3 implant surface was not observed. Instead, apatitic smooth-shaped crystals formed in aggregates. The coral dissolution process does not release phosphate and so precipitation of apatite does not occur in the micropores of the coral implant, thereby limiting the formation of an apatite layer and hence bone bonding to the outer surface of the implant. In addition, on the outer surface of the implant, close to bone and a phosphorus source, the CaP crystals that do form are in aggregates presumably due to the carbonate and mismatch between the aragonite and the apatite. This seems to result in a delayed bone attachment or weaker bone bonding than CaP implants which encourage an epitaxial biological crystal deposition.

Oncostatin M stimulates macrophage-polykaryon formation in long-term human bone-marrow cultures.

Though oncostatin M (OSM) is a potent mediator of the inflammatory reaction, its role in inflammation and bone resorption is still unclear. A long-term bone-marrow culture system is usually developed to allow the formation of multinucleated cells (MNC) and was used here to define the effects of human recombinant OSM on human MNC formation. OSM significantly upregulated (1.9- to 5.6-fold) the number of MNC in these cultures in a dose- and time-dependent manner. Cell nucleation and tartrate-resistant acid phosphatase activity were also increased. MNC did not display osteoclast characteristics, such as response to calcitonin and failure to resorb dentin surface. However, they expressed a non-specific alpha-naphthyl acetate esterase as well as macrophage differentiation antigens (CD11b, CD13 and CD33) and were able to perform phagocytosis. Similar effects were observed after addition of 1 alpha, 25-dihydroxyvitamin D3. Moreover, in these culture conditions, human bone-marrow mononuclear cells were capable of low-grade resorption in the presence of bone-marrow stromal cells. This low-grade resorption was significantly inhibited by addition of 25 ng/ml OSM. Our data demonstrate for the first time that human recombinant OSM significantly stimulates the formation of MNC and could be involved in the inflammatory process via macrophage-polykaryon formation from human bone marrow.

Ultrastructural study of degradation of calcium phosphate ceramic by human monocytes and modulation of this activity by HILDA/LIF cytokine.

Biodegradation of ceramics in vivo is achieved essentially by monocytes and multinuclear cells (osteoclasts). Monocytes are the key element in this process because they intervene first at the biomaterial implantation site during inflammatory reaction. In this work, in vitro studies were conducted on an ultrastructural scale to determine the specific behavior of these cells with regard to a calcium phosphate (CaP) ceramic. Two types of phagocytosis were observed when cells came into contact with the biomaterial: either CaP crystals were taken up alone and then dissolved in the cytoplasm after disappearance of the phagosome membrane or they were incorporated together with large quantities of culture medium, in which case dissolution occurred after the formation of heterophagosomes. Phagocytosis of CaP coincided with autophagy and the accumulation of residual bodies in the cells. Addition of HILDA/LIF factor to these cultures induced a very marked decrease in phagocytotic activity directed at the capture of CaP crystals and culture medium. Autophagy was reduced, and residual bodies were rare or absent. This study specifies the role of monocytes in CaP biodegradation and demonstrates for the first time that HILDA/LIF has a biological effect on this cell line.

[The structure, ultrastructure and physicochemical analysis of the hard dental tissues of the Viperidae]. / Structure, ultrastructure et analyses physico-chimiques des tissus durs dentaires des vipéridés.

The present study, using classical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, has shown the dental hard tissues of the fangs of Viperidae (poisonous serpents with terrestrial or semi-aquatic habits) to be constituted of: a calcified outer layer, 0.4 microns thick, made of very small needle-like crystals, randomly distributed. The calcified outer layer contains organic invaginations inducing pores at the surface and many collagen fibres incompletely mineralized, which may suggest enameloid. a calcified inner layer, in the wall of the poison canal. The calcified inner layer, 0.6 microns thick, is constituted of very small crystals, which are parallel to each other and perpendicular to the calcified outer layer. It might be the inner layer of enameloid, an orthodentine, whose tubules present a special lateral branching system resembling a fish bone. The TEM data, which show the dentine to be constituted of very small ill-defined crystals and incompletely mineralized collagen fibres are corroborated by chemical analyses which reveal a poorly mineralized apatite with high carbonate content.

[The structure and ultrastructure of the pulp in Vipera aspis (Viperidae)]. / Structure et ultrastructure de la pulpe de Vipera aspis (Viperidae).

The present paper using classical and transmission electron microscopy brings the first data on the pulp of the fangs of Viperidae (poisonous serpents with terrestrial or semi-aquatic habits). The pulp of the fangs of Viperidae shows a poor collagen and fibroblast content and a high developed vascular system. The odontoblasts are polarized, with a high organelle content. The interconnections are constituted of lateral "gap junction" systems. At a late secretion stage, the odontoblastic processes show a poor cytoplasm, mainly constituted of microfilaments.