Co-ordinated expression of lymphoid and myeloid specific transcription factors during B-1b cell differentiation into mononuclear phagocytes in vitro IntroductionThe distinct origins, properties and fates of myeloid and lymphoid cell lineages have been clearly established since the beginning of the 1970s.1,2 Pluripotent haematopoietic stem cells give rise to all mature blood cell types through a stepwise process of binary decisions, in which multipotent progenitors undergo lineage commitment, branching into an intermediate progenitor that develops along a single pathway.1,2 It is hypothesized that the first decision of haematopoietic stem cells determines their fate as either lymphoid or myeloid cells. The lineage commitment is thought to be an irreversible process, restricting the developmental fate of a progenitor cell to a single lineage by mutual antagonism of lineagespecific transcription factors.2 Nevertheless, there is evidence that, in CD5 + -derived lymphomas, pre-B cells acquire macrophage characteristics in vitro and 'monocytoid B lymphocytes' have also been found to be associated with human diseases such as AIDS, chronic lymphocytic leukaemia, Sjögren's syndrome and Hodgkin's disease. [3][4][5][6] This bipotential phenotype could be considered a consequence of inadequate gene expression related to malignancy of these cells.However, the discovery of B-1 cells by Hayakawa et al. 7 disproved this hypothesis. B-1 cells were originally identified in the murine peritoneum, as a B-lymphocyte subset that differs from conventional B-2 cells or B lymphocytes in terms of phenotypic, functional and developmental characteristics. These differences have been extensively reviewed. [8][9][10][11][12] A striking distinction between these cells is that the immunoglobulin repertoire of B-1 cells is less diverse compared with that of B-2 cells. B-1 cells tend to express B-cell receptors with particular specificities; for example, approximately 10-15% of peritoneal B-1 cells are specific for the membrane phospholipid phosphatidylcholine. This specificity is commonly produced by the heavy chain variable (V) genes VH11 and VH12, which are expressed at high levels in B-1 cells, but not in B-2 cells.

Induction of adult rat bone marrow mesenchymal stem cells (MSC) by means of chemical compounds (β-mercaptoethanol, dimethyl sulfoxide and butylated hydroxyanizole) has been proposed to lead to neuronal transdifferentiation, and this protocol has been broadly used by several laboratories worldwide. Only a few hours of MSC chemical induction using this protocol is sufficient for the acquisition of neuronal-like morphology and neuronal protein expression. However, given that cell death is abundant, we hypothesize that, rather than true neuronal differentiation, this particular protocol leads to cellular toxic effects. We confirm that the induced cells with neuronal-like morphology positively stained for NF-200, S100, β-tubulin III, NSE and MAP-2 proteins. However, the morphological and molecular changes after chemical induction are also associated with an increase in the apoptosis of over 50% of the plated cells after 24 h. Moreover, increased intracellular cysteine after treatment indicates an impairment of redox circuitry during chemical induction, and in vitro electrophysiological recordings (patch-clamp) of the chemically induced MSC did not indicate neuronal properties as these cells do not exhibit Na+ or K+ currents and do not fire action potentials. Our findings suggest that a disruption of redox circuitry plays an important role in this specific chemical induction protocol, which might result in cytoskeletal alterations and loss of functional ion-gated channels followed by cell death. Despite the neuronal-like morphology and neural protein expression, induced rat bone marrow MSC do not have basic functional neuronal properties, although it is still plausible that other methods of induction and/or sources of MSC can achieve a successful neuronal differentiation in vitro.

Among the Brazilian population, the frequency rates of inherited retinal dystrophies and their causative genes are underreported. To increase the knowledge about these dystrophies in our population, we retrospectively studied the medical records of 1,246 Brazilian patients with hereditary retinopathies during 20 years of specialized outpatient clinic care. Of these patients, 559 had undergone at least one genetic test. In this cohort, the most prevalent dystrophies were non-syndromic retinitis pigmentosa (35%), Stargardt disease (21%), Leber congenital amaurosis (9%), and syndromic inherited retinal dystrophies (12%). Most patients had never undergone genetic testing (55%), and among the individuals with molecular test results, 28.4% had negative or inconclusive results compared to 71.6% with a conclusive molecular diagnosis. ABCA4 was the most frequent disease-causing gene, accounting for 20% of the positive cases. Pathogenic variants also occurred frequently in the CEP290, USH2A, CRB1, RPGR, and CHM genes. The relative frequency rates of different inherited retinal dystrophies in Brazil are similar to those found globally. Although mutations in more than 250 genes lead to hereditary retinopathies, only 66 genes were responsible for 70% of the cases, which indicated that smaller and cheaper gene panels can be just as effective and provide more affordable solutions for implementation by the Brazilian public health system.

Neural progenitor cells were isolated from rat fetal telencephalon and proliferate as neurospheres in the presence of EGF, FGF-2, and heparin. In the absence of these growth factors, neurospheres differentiate into neurons, astrocytes, and oligodendrocytes. Using an embryonal carcinoma cell line as in vitro differentiation model, we have already demonstrated the presence of an autocrine loop system between kinin-B2 receptor activity and secretion of its ligand bradykinin (BK) as prerequisites for final neuronal differentiation (Martins et al., J Biol Chem 2005; 280: 19576-19586). The aim of this study was to verify the activity of the kallikrein-kinin system (KKS) during neural progenitor cell differentiation. Immunofluorescence studies and flow cytometry analysis revealed increases in glial fibrillary acidic protein and b-3 tubulin expression and decrease in the number of nestin-positive cells along neurospheres differentiation, indicating the transition of neural progenitor cells to astrocytes and neurons. Kinin-B2 receptor expression and activity, secretion of BK into the medium, and presence of highmolecular weight kininogen suggest the participation of the KKS in neurosphere differentiation. Functional kinin-B2 receptors and BK secretion indicate an autocrine loop during neurosphere differentiation to neurons, astrocytes, and oligodendrocytes, reflecting events occurring during early brain development. ' 2008 International Society for Analytical CytologyKey terms kinin-B2 receptor; neural differentiation; neurosphere; kallikrein-kinin system BRADYKININ (BK), kallidin, des-Arg 9 -BK, and des-Arg 9 -kallidin are the biological active peptides of the kallikrein-kinin system (KKS). BK and kallidin as ligands of Gprotein-coupled kinin-B2 receptors (B2BKR) are generated upon proteolytic cleavage of high-or low-molecular weight kininogen (HMWK or LMWK) by plasma-or tissue-kallikrein serine protease, respectively. Carboxy-terminal arginines are removed from these biological active peptides by carboxypeptidases M or N to originate the kinin-B1 receptor (B1BKR) agonists des-Arg 9 -BK and des-Arg 9 -kallidin (Fig. 1). Stimulation of the B2BKR by its agonists results in the activation of phospholipase C-b (PLC-b), generating diacyl glycerol and inositol 1,4,5-triphosphate (IP 3 ) and resulting in release of Ca 21 from intracellular IP 3 -sensitive stores. Furthermore, BK mediates the activation of endothelial nitric oxide synthase (1) and stimulates the phospholipase A2 activity (2). B2BKR also activates proteins with tyrosine kinase activity (3), and the receptor can directly interact with neuronal and endothelial nitric oxide synthetase (nNOS and eNOS), resulting in NO production (4). Both B1BKR and B2BKR are coupled to G aq and G ai proteins (5,6) and triggered the same signaling pathways, but differ in their expression pattern and intensities of receptorinduced calcium responses and receptor-desensitization rates (7).B2BKR is constitutively expressed and broadly distributed throughout the tissues, and B1BK...