Occupational identity crisis of professionals dealing with difficult adolescents.

This study tests the hypothesis of vulnerability in health and social care professionals dealing with difficult adolescents. This vulnerability appears to be underpinned by an occupational identity crisis that seems to diminish the ability of these professionals to recognize the suffering of these adolescents. A questionnaire was developed and then distributed during a network day bringing together members of various institutions and bodies working with difficult adolescents. Ninety-three professionals responded. Occupational identity weaknesses were identified: inadequate basic training, experiences of solitude, feelings of powerlessness and exposure, inadequate personal and institutional resources. Actors involved express their need for inter-institutional and inter-sectoral network but find it uneasy to implement. Some changes can be recommended to reduce this occupational identity crisis: increased efforts towards continuing training, development of possibilities of reflection within institutions, and more structured partnerships and actions.

Experimental evidence of the electrostatic contribution to the bending rigidity of charged membranes.

We address the issue of the origin of the bending rigidity of a charged membrane formed from amphiphilic molecules. Electrostatic effects are investigated by direct measurement of the force necessary to deform a catanionic membrane as function of the ionic strength of the medium by means of an atomic force microscope (AFM). Using continuum mechanical modeling of membrane deformation, we derive the bending rigidity of the catanionic membranes and monitor for the first time its decrease in response to increasing salt concentration.

Anti-lactoferrin autoantibodies: relation between epitopes and iron-binding domain.

Anti-neutrophil cytoplasm antibodies (ANCA) have been found in the sera of patients presenting systemic necrotizing microscopic vasculitis, i.e. Wegener's granulomatosis and microscopic polyangiitis. Lactoferrin (LF) is one of the antigens rarely recognized by ANCA, and anti-LF autoantibodies are found in several autoimmune conditions, including rheumatoid vasculitis, rheumatoid arthritis, systemic lupus erythematosus, ulcerative colitis, primary sclerosing cholangitis and Crohn's disease. We analysed the epitopes recognized by human anti-LF antibodies to test whether the heterogeneity of clinical presentation might be due to a different epitope recognition profile. Several monoclonal antibodies were raised and used in competition studies with six human sera. Four distinct epitopes were identified on LF, and LF binding of only one of six sera was inhibited by one of the monoclonals. Thus, anti-LF autoreactivity appears to be polyclonal and not restricted to an immunodominant epitope. Specific epitope profiles cannot be determined in these autoimmune conditions. We hypothesized that the interaction of anti-LF antibodies with the LF iron binding domain might contribute to pathogenesis by inhibiting iron chelation after neutrophil activation, thereby providing increased iron availability for endothelial cell damage. The relation of anti-LF mouse monoclonals or polyclonal human or rabbit antibodies to the LF iron-binding domain was studied in competition assays between 59Fe and these antibodies. Preincubation of LF with monoclonals or anti-LF human sera did not affect the binding of 59Fe on LF. 59Fe-binding kinetic studies showed that rabbit anti-LF polyclonal, but not mouse monoclonals or human anti-LF positive sera, was capable of inhibiting iron binding on LF. Therefore, anti-LF autoantibodies did not appear to modulate LF iron-binding activity. We conclude that LF is a rare antigen specificity for ANCA and that the clinical and pathophysiological relevance of anti-LF autoreactivity remains uncertain.

Flow cytometry analysis of dual red blood cell populations after bone marrow transplantation.

Flow cytometry represents an alternative method to agglutination assays for the accurate quantification of mixed field populations of erythrocytes observed after bone marrow transplantation. Murine monoclonal antibodies directed against the blood group ABH antigens were selected and processed in order to prepare ready-to-use fluorescent reagents. Anti-A (NaM87-1F6; IgG3), anti-B (NaM9-2E11; IgG3) and anti-H (NaM19-7E11; IgM) were purified, labelled with fluorescein isothiocyanate, and used in a direct flow cytometry assay. Anti-A1 (NaM1-1C9; IgG3) was no longer active after FITC-labelling and then was used in an indirect assay. The agglutination was prevented by formaldehyde pretreatment of erythrocytes. Using artificially-made double populations of erythrocytes, measured values with mixtures of 1-100% of cells were very closely related to expected values, showing both the sensitivity and the accuracy of the method. From careful investigation of a series of bone-marrow transplanted patients, we conclude that engraftments could be demonstrated earlier by flow cytometry than by agglutination, because minor populations (1-10%) of cells could be determined accurately only with labelled reagents. In addition, the disappearance of the donor cells on a long-term follow-up of patients enabled an earlier detection of graft failure in one case. The proposed method provides appreciable help to follow engraftment in patients and may have more general applications for the study of other haemopoietic chimaeras.

Variation in fetal hemoglobin parameters and predicted hemoglobin S polymerization in sickle cell children in the first two years of life: Parisian Prospective Study on Sickle Cell Disease.

Intracellular hemoglobin S (HbS) polymerization is most likely to be the primary determinant of the clinical and biologic manifestations of sickle cell disease (SCD). Fetal hemoglobin (HbF) does not enter the HbS polymer and its intracellular expression in sickle erythrocytes inhibits polymerization. HbF levels, high at birth but decreasing thereafter, protect the newborn from the clinical manifestations of this hemoglobinopathy. We have measured the sequential changes in HbF, F reticulocytes, and F cells in the first 2 years of life in 25 children with SCD and compared the results with those obtained in 30 normal children (AA). We have also calculated HbF per F cell (F/F cell), the preferential survival of F cells versus non-F cells, as measured by the ratio F cells versus F reticulocytes (FC/FR) and polymer tendency at 40% and 70% oxygen saturation. HbF levels decreased from about 80.4% +/- 4.0% at birth to 9.2% +/- 2.9% at 24 months. During this time, we observed a regular decrease of the F reticulocytes and the F cells. The kinetics of the decline of F/F cell was comparable with the decline of HbF, rapid from birth (mean, 27.0 +/- 3.6 pg) to 12 months of age (mean, 8.5 +/- 1.5 pg) and then slower from 12 to 24 months of age (mean, 6.2 +/- 1.0 pg) in the SCD children. In the AA children, the decrease in HbF, due to changes in both numbers of F cells and F/F cell, was more precipitous, reaching steady-state levels by 10 months of age. Calculated values for mean polymer tendency in the F-cell population showed that polymerization should begin to occur at 40% oxygen saturation at about 3 months and increase progressively with age, whereas polymerization at 70% oxygen saturation would not occur until about 24 months. These values correspond to HbF levels of 50.8% +/- 10.8% and 9.2% +/- 2.9%, respectively, and F/F cell levels of 15.6 +/- 4.5 pg and 6.2 +/- 1.0 pg, respectively. In the non--F-cell population, polymerization was expected at birth at both oxygen saturation values. Three individuals had significantly greater predicted polymerization tendency than the remainder of the group because of early decreases in HbF. These individuals in particular, the remainder of the cohort, as well as other recruited newborns, will be studied prospectively to ascertain the relationship among hematologic parameters, which determine polymerization tendency and the various clinical manifestations of SCD.

A murine monoclonal antibody directed against the Gerbich 3 blood group antigen.

A murine monoclonal antibody (NaM19-3C4, IgG1, Kappa) was produced from splenocytes of mice immunized with red blood cells. The antibody agglutinated untreated Ge:2,3,4 and Ge:-2,3,4 erythrocytes in indirect antiglobulin test but failed to agglutinate trypsin-treated cells. Gerbich-negative erythrocyte of the Leach- (Ge:-2,-3,-4) and of the Gerbich- (Ge:-2,-3,4) types were not recognized by the antibody. Immunoblotting experiments showed that the antibody bound to glycophorins C and D from control erythrocytes and to the abnormal glycophorin C identified in the Gerbich-negative cells of the Yussef type (Ge:-2,3,4). No binding to the altered glycophorin C from Ge:-2,-3,4 erythrocytes was observed, indicating that the antibody specifically recognized the Ge:3 epitope localized within residues 40-50 of glycophorin C.