Bacteremia due to a novel Microbacterium species in a patient with leukemia and description of Microbacterium paraoxydans sp. nov

A yellow-pigmented coryneform rod was isolated from the blood of a child with acute lymphoblastic leukemia who was perfused with a central venous catheter. The culture bottles were positive twice, at a 2-month interval. The isolate was identified as a Microbacterium sp. and studied along with five other similar strains. Phenotypic, chemotaxonomic, and genetic characteristics indicated that they are closely related to Microbacterium oxydans but that they belong to a distinct species, for which the name Microbacterium paraoxydans sp. nov. is proposed. The type strain of M. paraoxydans is CF36(T) = DSM 15019(T). The G+C content of its DNA is 69.9 mol%.     

Evaluation of the professional practices of physicians in transfusion technology and medicine]

The evaluation of the professional practices (EPP) is obligatory for all the physicians since July 1, 2005 for a first five-year period. It represents one of the components of the continuous medical training (CMT). The French Society of Blood Transfusion and National Institute of Blood Transfusion are the promoters of the EPP in transfusion technology and medicine. Initially, the programs of EPP will be conceived and controlled by experts and will relate to their basic activities. During a five years cycle, the physician taking part in a program must validate a specific action and take part in a rolling programme. At the end of the programme, the physician will receive a certificate issued by National Institute of Blood Transfusion and will have to submit it to a committee placed under the responsibility of the regional physicians' committee.     

Ly49E expression points toward overlapping,but distinct,natural killer (NK) cell differentiation kinetics and potential of fetal versus adult lymphoid progenitors

Using a new antibody, we found previously that contrary to adult natural killer (NK) cells, fetal NK cells have a unique phenotype, as they exclusively express Ly49E. This can be explained by an intrinsic different NK differentiation potential of fetal versus adult lymphoid progenitors, by immaturity of fetal NK cells or by instability of Ly49E expression. Here, we show that adult progenitor cells were still capable of differentiating into Ly49E-expressing NK cells but at a much lower frequency. Surprisingly, Ly49E expression in vitro did not require stromal cells. Kinetic analysis in vivo showed that Ly49E was expressed early, together with CD94/NKG2 and Ly49G2, followed by Ly49C, and finally Ly49D. Transfer of sorted Ly49E-positive fetal NK cells showed stable Ly49E expression, and later, part of these cells up-regulated other Ly49 members. These data indicate that although there are intrinsic differences, there is no strict fetal and adult wave of NK cell differentiation.     

Ring chromosome 6 as the only change in a thymoma

Cytogenetic analysis of a thymoma showed the presence of a ring chromosome 6 as the sole chromosome abnormality. © 1993 Wiley-Liss, Inc.     

The dragon lizard <Emphasis Type="Italic">Pogona vitticeps</Emphasis> has ZZ/ZW micro-sex chromosomes

The bearded dragon, Pogona vitticeps (Agamidae: Reptilia) is an agamid lizard endemic to Australia. Like crocodilians and many turtles, temperature-dependent sex determination (TSD) is common in agamid lizards, although many species have genotypic sex determination (GSD). P. vitticeps is reported to have GSD, but no detectable sex chromosomes. Here we used molecular cytogenetic and differential banding techniques to reveal sex chromosomes in this species. Comparative genomic hybridization (CGH), GTG- and C-banding identified a highly heterochromatic microchromosome specific to females, demonstrating female heterogamety (ZZ/ZW) in this species. We isolated the P. vitticeps W chromosome by microdissection, re-amplified the DNA and used it to paint the W. No unpaired bivalents were detected in male synaptonemal complexes at meiotic pachytene, confirming male homogamety. We conclude that P. vitticeps has differentiated previously unidentifable W and Z micro-sex chromosomes, the first to be demonstrated in an agamid lizard. Our finding implies that heterochromatinization of the heterogametic chromosome occurred during sex chromosome differentiation in this species, as is the case in some lizards and many snakes, as well as in birds and mammals. Many GSD reptiles with cryptic sex chromosomes may also prove to have micro-sex chromosomes. Reptile microchromosomes, long dismissed as non-functional minutiae and often omitted from karyotypes, therefore deserve closer scrutiny with new and more sensitive techniques.     

Role of NK cells and gamma interferon in transplacental passage of Toxoplasma gondii in a mouse model of primary infection

Protective immunity in mice infected with Toxoplasma gondii is mainly mediated by NK cells, CD4 and CD8 T cells, and type 1 cytokines, such as gamma interferon (IFN-gamma). To clarify the roles of NK cells and IFN-gamma in protection against primary congenital toxoplasmosis, we used recombination activating gene 2 knockout (RAG-2(-/-)) mice, which lack T and B lymphocytes, in comparison with the wild-type BALB/c model. RAG-2(-/-) mice had a significantly lower risk of fetal toxoplasmosis than BALB/c mice (25 versus 63.9%; P = 0.003). This protection was associated with an increased number of maternal NK cells, IFN-gamma secretion by spleen cells, and decreased parasitemia. In the RAG-2(-/-) mice, NK cell depletion increased both the rate of fetal infection, to 56.5% (P = 0.02), and the blood parasite burden. Conversely, in the BALB/c mice, this treatment did not modify maternofetal transmission or the blood parasite burden. Neutralization of IFN-gamma in both infected RAG-2(-/-) and BALB/c mice decreased congenital Toxoplasma transmission, contrasting with an exacerbation of maternal infection. These data suggest that a partially protective immunity against congenital toxoplasmosis is achieved due to the increased number of NK cells in RAG-2(-/-) mice. However, it seems that IFN-gamma enhances, directly or indirectly, the transplacental transmission.     

Transformation of B and non-B cell lines with the 2,4,6,-trinitrophenyl (TNP)-specific immunoglobulin genes

The rearranged mu and kappa genes from the 2,4,6-trinitrophenyl (TNP)-specific hybridoma Sp6 have been introduced into B cells from three different stages of differentiation as well as 5 non-B cell lines to determine the levels and modes of immunoglobulin (Ig) gene expression. In pre-B cells transformed with the mu and kappa genes, low levels of Sp6-specific mu RNA were produced and approximately 210-fold less mu and 800-fold less kappa proteins were produced than in the hybridoma Sp6. The Ig proteins were present intracellularly, but were not detected on the cell membrane. In mature surface sIg+ B cell transformants, higher levels of mu Sp6 and kappa Sp6 proteins and RNA were produced than in the pre-B cell transformants (12 X mu, 70 X kappa). These transformants displayed the mu Sp6 and kappa Sp6 proteins on the cell membrane and also secreted the transfected Ig product. Plasma cell transformants produced the highest amounts of mu Sp6 and kappa Sp6 proteins. These transformants secreted pentameric IgM but did not display detectable amounts of these proteins on the cell membrane. T cell and one fibroblast transformant produced Ig as normal sized mu Sp6 and kappa Sp6 proteins. All other mu Sp6 and kappa Sp6 non-B cell transformants (melanoma, teratoma and macrophage) failed to produce enough Ig to determine whether the Ig proteins were of the correct molecular weights. The T cell and fibroblast transformants that produced Ig proteins did not secrete or display detectable Ig on the cell membrane. The expression of Ig did not inhibit the expression of the T cell antigen Thy-1 in the T cell transformants.     

Monosomy 9q and trisomy 16q in a case of congenital solitary infantile myofibromatosis

Although infantile myofibromatosis (IM) is the most common fibrous proliferation of infancy, many aspects of this benign lesion have not been explored. IM histogenesis is still poorly understood, despite immunohistochemical staining and ultrastructural features that suggest a myofibroblastic origin. IM diagnosis is often made difficult by the predominance of small primitive spindle cells over myofibrobasts and the presence of intravascular growth. Genetic information is scarce, with only one karyotyped case. Here we describe a case of solitary IM discovered at birth in an otherwise healthy girl. The tumor was well circumscribed, arranged in nodules and made up of ovoid cells without atypia, in a myxoid background. Immunohistochemical evaluation indicated a myofibroblastic differentiation. The cytogenetic and fluorescence in situ hybridization analyses revealed an abnormal chromosome 9, derived from an unbalanced whole-arm translocation between chromosomes 9 and 16. On both chromosomes, the breakpoints were located in the pericentric heterochromatic region. This clonal abnormality has not been reported in other tumors and is different from the chromosome 6q deletion reported in the single previous reported IM karyotype.