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B Melchior

Publications and source records attributed to B Melchior.

6 recordsLinked to original sources
PubMed2001

Different mechanisms mediate the rejection of porcine neurons and endothelial cells transplanted into the rat brain.

In order to investigate the early cellular responses mediating xenograft rejection in the brain, porcine aortic endothelial cells (PAEC) or porcine fetal mesencephalic neurons (PNEU) were transplanted into the striatum of LEW.1A rats. PAEC were detected with a specific anti-beta1 integrin antibody, and PNEU with an anti-porcine neurofilament antibody, or an antibody recognizing the NeuN antigen. PAEC grafts were massively infiltrated within 24 h by OX42-positive cells, which may correspond to polymorphonuclear (PMN) cells or macrophages. At that moment, the graft contained numerous cells expressing the inducible isoform of NO-synthase (iNOS). Infiltration by ED1-positive macrophages was effective after three days. The beta1-integrin labeling decreased from that time-point to day 7 post-implantation, and vanished after 11 days. Although some OX8-positive cells were present around the graft as soon as 3 days after transplantation, cells expressing the T-cell receptor (TCR)-beta chain infiltrated the graft after 7 days and their number remained low. A strong, diffuse OX8-and ED1-positive immunoreactive material remained in the scar up to the third week. In striking contrast, PNEU grafts remained poorly infiltrated by OX42- or ED1-positive cells during the first two weeks. A massive infiltration by macrophages and TCRbeta-positive lymphocytes occurred after 3 weeks. Natural killer (NK) cells were more scarce. The inflammation territory enlarged, and blood vessels were overloaded with macrophages or lymphocytes. Nevertheless, the graft contained NeuN-positive nuclei and neurites harbouring the porcine neurofilament protein. Hence, rejection was not completed at this time-point. These results suggest that the rapid rejection of PAEC is mainly driven by macrophages and possibly PMN cells, unlike PNEU, whose rejection is delayed and also involves lymphocytes. Differences in immunogenicity of grafted cells and/or patterns of production of pro-inflammatory cytokines may account for these contrasted rejection kinetics.

Animals↗
PubMed1992

[Bone hemangioma of the limbs. A report of two cases in children].

Hemangiomas of bone are rare lesions corresponding approximately to 1% of all primary bone tumors. Cases of hemangiomas in the vertebral bodies and in the skull occur fairly frequently but are unusual in other bones. The authors reported two cases of unusual and fairly rare aspects of this vascular tumor in children. In both cases, recurrences occurred and leaded to a wide bone resection in case one and to several curettage in case two. In these two case the histological type of hemangioma was the capillary one. In reviewing the literature we found no indication for wide resection of the benign forms in children.

Adolescent↗
PubMed1992

[Impact of angiodysplasia on bones].

Vascular malformations usually have an impact on bones because of hemodynamic disturbances in the muscular and osteoperiosteal systems. In fact, even when these structures are not involved by arterial or venous malformations, the blood flow is altered in them. The consequences for bones affect the longitudinal growth of the skeleton of the malformed limb. Growth rarely becomes slower. On the contrary, the condition usually results in an acceleration of bone growth, which results in an excess in the length of the limb presenting with the vascular malformation. This overlengthening may be variably great, and the therapeutic indications must be adapted to its extent. When it is slight, compensation is sufficient to balance the pelvis. Conversely, when it is greater, its correction must be surgical. This surgery is aimed at equalizing the lower limbs, either by slowing down epiphyseal growth and shortening the longer side, or by progressively lengthening the other side, as the case may be. The respective indications of these methods must be carefully considered and adapted to each case, in order to obtain the best possible result with the smallest surgical risk.

Arteriovenous Malformations↗
PubMed1990

[Epiphyseal fractures-dislocations of the lower extremity of the tibia].

Ninety six distal tibial epiphyseal fractures were identified and treated in our institution from 1976 to 1988. The average age was twelve years and eight months (range two to seventeen years), but seventy-one were between eleven and fourteen years old. Using the Salter-Harris classification we have found twelve type 1 tibial fractures, fourty-two type 2, thirty type 3 and twelve type 4. Four were triplane fractures and seven were Tillaux fractures. Twenty-six had injuries in the medial corner of the ankle mortise (Mac-Farland). Fifty patients were treated non-operatively with closed reduction and plaster cast. Fourty-six fractures were treated surgically. Seventy patients were available for follow-up evaluation. The average follow-up was thirty-two months (range 6 months to eleven years). The tibial distal epiphyseal cartilage was closed in 48 patients. As short-term complications we have seen three post-operative displacements after closed reduction; all of them were treated surgically. Five incomplete closed reduction needed open reduction needed open reduction and bone fixation. Two infections occurred after a surgical approach. Among late complications we have seen eleven premature epiphyseal cartilage closure (rate 15%). Four were responsible of angular deformities. One child has a tibial osteotomy for varus deformity after a medial closure. Two ankle arthritis occurred: one of them was seen after a post-operative infection. In two cases of fracture of the medial mortise corner, a valgus deformity with hypertrophy of the medial malleolus occurred. Ankle arthritis is the most severe complication of the adolescent articular fractures (Tillaux and triplane fractures).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Lower limb bone hemangiomas in children: report of two cases.

Hemangiomas of the bone are rare lesions, accounting for approximately 1% of all primary bone tumors. Hemangiomas occur fairly frequently in the vertebral bodies and the skull, but are unusual in other bones. We report two cases of unusual and fairly rare aspects of this vascular tumor in children. Both cases involved recurrences, which led to a wide bone resection in case 1 and to several curettages in case 2. In these two cases the histological type of hemangioma was capillary. In reviewing the literature we found no indication of wide resection of the benign forms in children.

Adolescent↗