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In aplastic anaemia ( AA), haemopoietic activity is significantly reduced and generally attributed to failure of haemopoietic stem cells ( HSC) within the bone marrow ( BM). The regulation of haemopoiesis depends on the interaction between HSC and various cells of the BM microenvironment, including mesenchymal stromal cells ( MSC). MSC involvement in the functional restriction of HSC in AA is largely unknown and therefore, the physical and functional properties of AA MSC were studied in vitro. MSC were characterized by their phenotype and ability to form adherent stromal layers. The functional properties of AA MSC were assessed through proliferative, clonogenic and cross-over culture assays. Results indicate that although AA MSC presented typical morphology and distinctive mesenchymal markers, stromal formation was reduced, with 50% of BM samples failing to produce adherent layers. Furthermore, their proliferative and clonogenic capacity was markedly decreased ( P = 0·03 and P = 0·04 respectively) and the ability to sustain haemopoiesis was significantly reduced, as assessed by total cell proliferation ( P = 0·032 and P = 0·019 at Week 5 and 6, respectively) and clonogenic potential of HSC ( P = 0·02 at Week 6). It was concluded that the biological characteristics of AA MSC are different from those of control MSC and their in vitro haemopoiesis-supporting ability is significantly reduced. [ABSTRACT FROM AUTHOR]

The HOX genes are key determinants of cellular identity both in early development and in the renewal and differentiation of adult blood cells. Although a number of studies have examined the expression of individual HOX genes in defined blood cell lineages, we have undertaken a comprehensive analysis of HOX gene expression in resting and activated lymphocytic and monocytic subpopulations. This has revealed distinct patterns of expression between different cell types and resting and activated states. (Main category A: Erythrocytes, Leukocytes and Hematopoiesis, subcategory: 8: Lymphocytes). [ABSTRACT FROM AUTHOR]

Summary. Determining the cellular distribution of key adhesion molecules may aid in understanding haematopoietic progenitor/stem cell (HPSC) homing to bone marrow (BM). CD34, a well-characterized marker for blast-like HPSC, is widely used for the isolation and enumeration of HPSC. Functional studies have yet to identify a ligand for CD34. However, growing evidence suggests that CD34 may aid the regulation of HPSC differentiation and modulate the expression of other HPSC adhesion molecules necessary for homing. This study aimed to determine CD34 distribution on umbilical cord blood (CB) and BM. CD34-selected cells were adhered to positively charged gold slides at room temperature, before indirect fluorescent antibody labelling with fluorescein isothiocyanate. Fluorescent distribution was determined by 1-µm interval, confocal laser scanning microscope Z-sections. Initial analysis showed CD34 distributed within peripheral halos and dense pocket regions. The development of three-dimensional imaging software enabled spatial visualization of CD34 distribution on CB and BM in association with differential interference contrast cell image. This showed that CD34 was distributed within peripheral halos, with magnupodia-associated ‘meridian-shaped crescents’, extending from points of cell–slide adhesion towards the top of the cell. True CD34 distribution, not previously discernible by confocal laser scanning microscopy alone, suggests a possible role in cell adhesion/homing revealed by three-dimensional imaging. [ABSTRACT FROM AUTHOR]

This article argues for a re-examination of the health service available to adolescents within schools so that it continues to meet needs, and is not duplicating services offered elsewhere. The author describes a two term trial of a successful model of working based on the early identification by teachers of adolescents with problems, their early assessment by the school doctor and joint planning of subsequent management by health, education and social work personnel. A large number of problems are identified and tackled with benefit to the teachers and doctor, as well as to the adolescents and their families. [ABSTRACT FROM AUTHOR]