Neural crest induction is thought to occur by a two-step process. Axially fated mesoderm induces neural plate, which is then recruited to neural crest by nonneural epidermal ectoderm at the neural plate border. This model suggests a rather indirect role for mesoderm in inducing neural crest. We extensively examined the role of mesoderm in neural crest induction by determining which types of mesoderm induce neural crest cells in Xenopus embryos. We found that noggin-dorsalized ventral marginal zone (VMZ) explants differentiate as melanocytes in the absence of axial mesoderm. Dorsalized VMZ is also a potent inducer of melanocytes when juxtaposed to animal cap ectoderm in recombinant explants. Dorsalized VMZ is analogous to the dorsal-lateral marginal zone (DLMZ) region of the embryo. Neural crest-inducing activities of gastrula stage DLMZ and dorsal marginal zone (DMZ) were also compared in recombinant explants. DLMZ was a stronger inducer of neural crest than was DMZ; DLMZ induced high levels of XSlug expression and melanocyte formation in recombinants, whereas DMZ weakly induced neural crest. In whole embryos lacking DLMZ, XSlug expression and melanocyte formation were significantly reduced; in contrast, no significant reduction of XSlug expression or melanocyte formation was seen in embryos lacking a DMZ. These results suggest that paraxial-fated mesoderm plays a central role in neural crest formation by inducing a novel type of lateral neural plate. This lateral neural plate is then recruited to neural crest by adjacent nonneural epidermal ectoderm.

A homologue of the Drosophila homothorax (hth) gene, Xenopus Meis3 (XMeis3), was cloned from Xenopus laevis. XMeis3 is expressed in a single stripe of cells in the early neural plate stage. By late neurula, the gene is expressed predominantly in rhombomeres two, three and four, and in the anterior spinal cord. Ectopic expression of RNA encoding XMeis3 protein causes anterior neural truncations with a concomitant expansion of hindbrain and spinal cord. Ectopic XMeis3 expression inhibits anterior neural induction in neuralized animal cap ectoderm explants without perturbing induction of pan-neural markers. In naive animal cap ectoderm, ectopic XMeis3 expression activates transcription of the posteriorly expressed neural markers, but not pan-neural markers. These results suggest that caudalizing proteins, such as XMeis3, can alter A-P patterning in the nervous system in the absence of neural induction. Regionally expressed proteins like XMeis3 could be required to overcome anterior signals and to specify posterior cell fates along the A-P axis.

No abstract

GTs are safe and should be considered for patients with life-threatening neutropenic infections. However, prospective randomized studies of GTs are the only way to establish the true role of GTs.

Acute infusion reactions are the most common documented adverse reactions reported with rituximab, with overt cytokine release syndrome, and hematological adverse events being much rarer. The clinical course of a patient with mantle cell lymphoma, who developed acute thrombocytopenia and leukopenia following rituximab administration, is described and the literature reviewed. Serum complement and the levels of three cytokines-TNF-a, IL-6, and IL-1, were measured 2 days after the infusion of rituximab by using ELISA assay. Drug-dependent antibodies against platelets were evaluated by two procedures as follows: an immunofluorescence test applying flow cytometry and Monoclonal Antibody Immobilization of Platelet Antigen (MAIPA). Serum levels of TNF-a were significantly increased compared with normal, whereas those of IL-6 and IL-1 were not increased significantly. Flow cytometry assay and the MAIPA assay failed to detect rituximab-dependent antibodies against platelets. Complement levels were decreased compared with normal. Literature search yielded 10 publications reporting on another 15 patients. The most common type of lymphoma was mantle cell lymphoma, six patients had bone marrow involvement, and 10 patients had splenomegaly. In 10 patients, acute cytopenia was preceded by cytokine release syndrome or infusion-related symptoms. Usually, thrombocytopenia was not associated with bleeding manifestations. Thrombocytopenia was the most commonly acute cytopenia reported. The postulated pathogenesis is associated with cytokine release syndrome and complement activation. Patients with potential risk factors like splenomegaly and bone marrow involvement, who develop clinical manifestations compatible with cytokine release syndrome, should be closely monitored for rituximab-associated cytopenia. Am. J. Hematol. 84:247-250, 2009. V

No abstract

Terrorist attacks in crowded places cause multiple casualties that are evacuated by quick succession to nearby hospitals. The study goals were to analyse the issues of patient misidentification and excessive blood request and to develop recommendations for the management of such episodes. A retrospective analysis of nine explosion attacks was performed. In nine consecutive events, 450 casualties were reported by the National Ambulance Service, 82 of whom (18%) died on the explosion site and 368 were admitted to nearby trauma centres. Red blood cell units were typed and cross-matched for 70 patients. Seventy-three per cent of the blood supplied over the first 24 h was administered during the first 2 h. The cross-matched/transfused ratio was 2.52 +/- 1.42, reflecting the overestimation of blood requirement in mass casualty episodes. In the mass casualty setup, blood bank personnel should be alert to a potential mistransfusion or a blood collection error. Unidentified patients are subjected to errors due to only one-digit difference in their temporary identification number. Application of the system using an additional sequential four-digit number printed in bold and large size font for patients at admission reduced the possibility of misidentification. Modern technologies, including error-reduction design wristbands, barcode-based system or radiofrequency identification tags may also increase reliability of patient identification in the mass casualty setup.

Checkpoint inhibitors effectively enhance the natural immune response against cancer, but they are also known to induce a unique spectrum of immune-related adverse events. Here, we report the first case of isolated neutropenia subsequent to nivolumab therapy. Prominent activated T-cells were found in the patient's serum and bone marrow alongside evidence of maturational defects in neutrophil precursors. Antineutrophil antibodies were not detected despite reliable testing techniques. A T-cell-mediated response is probable, consistent with the established mechanism for the development of other immune-related toxicities. Awareness of this rare and severe side effect reinforces the importance of early diagnosis and prompt initiation of proper treatment.