Quantum Storage of Single-Photon and Two-Photon Fock States with an All-Optical Quantum Memory.

Quantum memories are a crucial element toward efficient quantum protocols. In the continuous variables domain, such memories need to provide high fidelity with an efficiency set to one. Moreover, one needs to store complex quantum states exhibiting negative Wigner functions after storage. We report the storage of single- and two-photon Fock states in an all-optical quantum memory. The Wigner functions of these states show negativity after a storage time of several hundred nanoseconds. This is, to our knowledge, the first demonstration of the storage in the optical domain of non-Gaussian states with more than one photon, captured from an external source and characterized with homodyne detection.

A novel approach for the identification of efficient combination therapies in primary human acute myeloid leukemia specimens.

Appropriate culture methods for the interrogation of primary leukemic samples were hitherto lacking and current assays for compound screening are not adapted for large-scale investigation of synergistic combinations. In this study, we report a novel approach that efficiently distills synthetic lethal interactions between small molecules active on primary human acute myeloid leukemia (AML) specimens. In single-dose experiments and under culture conditions preserving leukemia stem cell activity, our strategy considerably reduces the number of tests needed for the identification of promising compound combinations. Initially conducted with a selected library of 5000 small molecules and 20 primary AML specimens, it reveals 5 broad classes of sensitized therapeutic target pathways along with their synergistic patient-specific fingerprints. This novel method opens new avenues for the development of AML personalized therapeutics and may be generalized to other tumor types, for which in vitro cancer stem cell cultures have been developed.

The TGF-ß-Smad3 pathway inhibits CD28-dependent cell growth and proliferation of CD4 T cells.

Transforming growth factor-ß (TGF-ß) maintains self-tolerance through a constitutive inhibitory effect on T-cell reactivity. In most physiological situations, the tolerogenic effects of TGF-ß depend on the canonical signaling molecule Smad3. To characterize how TGF-ß/Smad3 signaling contributes to maintenance of T-cell tolerance, we characterized the transcriptional landscape downstream of TGF-ß/Smad3 signaling in resting or activated CD4 T cells. We report that in the presence of TGF-ß, Smad3 modulates the expression of >400 transcripts. Notably, we identified 40 transcripts whose expression showed Smad3 dependence in both resting and activated cells. This 'signature' confirmed the non-redundant role of Smad3 in TGF-ß biology and identified both known and putative immunoregulatory genes. Moreover, we provide genomic and functional evidence that the TGF-ß/Smad3 pathway regulates T-cell activation and metabolism. In particular, we show that TGF-ß/Smad3 signaling dampens the effect of CD28 stimulation on T-cell growth and proliferation. The impact of TGF-ß/Smad3 signals on T-cell activation was similar to that of the mTOR inhibitor Rapamycin. Considering the importance of co-stimulation on the outcome of T-cell activation, we propose that TGF-ß-Smad3 signaling may maintain T-cell tolerance by suppressing co-stimulation-dependent mobilization of anabolic pathways.

A targeted association study in systemic lupus erythematosus identifies multiple susceptibility alleles.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease. Multiple genetic and environmental factors contribute to the pathogenesis of this disease. Recent genome-wide association studies have added substantially to the number of genes associated with SLE. To replicate some of these susceptibility loci, single-nucleotide polymorphisms reported to be associated to SLE were evaluated in a cohort of 245 well-phenotyped Canadian SLE trios. Our results replicate previously reported associations to alleles of interferon regulatory factor 5 (IRF5), major histocompatibility complex (MHC), tumor necrosis factor (ligand) superfamily member 4 (TNFSF4), Kell blood group complex subunit-related family member 6 (XKR6), B-cell scaffold protein with ankyrin repeats 1 (BANK1), protein tyrosine phosphatase non-receptor type 22 (PTPN22), ubiquitin-conjugating enzyme E2L 3 (UBE2L3) and islet cell autoantigen 1 (ICA1). We also identify putative associations to cytotoxic T-lymphocyte-associated protein 4 (CTLA4), a gene associated with several autoimmune disorders, and ERBB3, a locus on 12q13 that was previously reported to be associated with type 1 diabetes. This study confirms the existence of multiple genetic risk factors for SLE, and supports the notion that some risk factors for SLE are shared with other inflammatory disorders.

Improved leucoreduction of red blood cell units prepared after a 24-h hold with the platelet-rich plasma method using newly developed filters.

BACKGROUND AND OBJECTIVES: A previous study indicated that the extension of whole blood (WB) storage from 8 to 24 h at 20-24 degrees C before the processing of platelet-rich plasma (PRP)-depleted red blood cell (RBC) units had a negative effect on the efficacy of leucoreduction filters. In this study, we further characterized the phenomenon and tested the leucoreduction capacity of two newly developed filters. MATERIALS AND METHODS: Whole blood was stored at 20-24 degrees C and processed at 4-h intervals between 8 and 24 h postcollection. Components were leucoreduced before storage. Efficacy of novel filters to leucoreduce 24-h-hold PRP-depleted RBC units was also evaluated. RESULTS: Using a conventional filter, the mean residual white blood cell (WBC) counts in leucoreduced PRP-depleted RBCs were comparable in units prepared within 12 h from collection but gradually increased upon extended preprocessing storage from 0.36 +/- 0.03 at 12 h to 0.46 +/- 0.21, 0.76 +/- 0.54 and 1.72 +/- 1.76 x 10(6) per unit at 16, 20 and 24 h, respectively. However, the mean residual WBC content in 24-h-hold RBCs was reduced to 0.60 +/- 0.39 x 10(6) and 0.46 +/- 0.13 x 10(6) per units using RC2D and the prototypes B-1582 rev B filters, respectively. CONCLUSION: For PRP-depleted RBC units, the extension of the WB room temperature storage from 8 to 24 h before processing is likely to require the introduction of newly developed filters having an increased leucoreduction capacity in order to meet the maximal residual WBC guideline in the RBCs.

[Direct supervision. Perceptions of ex-residents in family medicine]. / La supervision directe. Perceptions d'ex-résidents en médecine familiale.

OBJECTIVE: To explore former residents' perceptions of their experience of direct supervision. DESIGN: Qualitative study using in-depth semistructured interviews. SETTING: Family practice unit (FPU) at Hôpital Laval in Quebec city, Que. PARTICIPANTS: Twelve physicians who had been practising for 2 to 5 years and who did their family medicine residency in the FPU at Hôpital Laval. METHOD: Twelve interviews lasting 1 to 2 hours conducted by someone with no connection to the teaching centre. Interviews were taped and transcribed in full. Results were analyzed using L'Ecuyer's developmental method. MAIN FINDINGS: The former residents thought direct supervision had helped them in relationships with patients and in getting to know themselves, and was still doing them good several years later. It was also a difficult and disturbing experience; it created performance anxiety, forcing residents into self-examination and allowing others to see them as they really are. Three things made the direct supervision process easier: a preparatory activity, a focus on learning rather than evaluation, and their supervisors' ability to adapt to their learning styles. CONCLUSION: The former residents appreciated direct supervision; in spite of the difficulties, it was worthwhile. This conclusion will encourage teachers to continue to be involved in direct supervision.

Staging of the commitment of murine cardiac cell progenitors.

The staging of murine cardiomyocyte specification and determination was investigated in cultures of tissue explants from pre- and postgastrulated embryos and after transplantation of cardiac or cardiogenic tissues from mouse embryos into 2-day-old chick embryos in different locations. The development of transplanted and cultured cells in cardiomyocytes was evaluated by testing the expression of several cardiac transcription factor genes (Nkx 2.5, eHAND, dHAND, GATA-4), alpha-cardiac actin mRNA, and beta-myosin heavy chain protein. In vitro analyses showed that cells with the potential to form cardiac muscle were present prior to gastrulation in 6.5-day postconception (dpc) epiblasts, as indicated by the expression of Nkx 2.5, eHAND, dHAND, and GATA-4 cardiac transcription factors; desmin transgene; alpha-cardiac actin; and beta-myosin heavy chain. Conversely, epiblasts transplanted into the chicken somitic environment did not exhibit full cardiogenic cell differentiation. It was determined that chick host axial structures did not influence cardiogenesis in transplants. Mesoderm from late streak explants was capable of differentiating into the cardiac phenotype in the avian heterotopic environment, indicating that the specification of cardiac precursors (under way by 6.5 dpc) became irreversible at around the late streak stage in mouse embryo. Although in vitro analyses showed that interaction with endoderm is not required for the specification of murine cardiac cells, the presence of endoderm in explant cultures between mid- and late streak stages stimulated emerging mesodermal cells to adopt a myocardial pathway, whereas ectoderm had no influence on cardiomyogenesis.

The expression of the homeobox gene Msx1 reveals two populations of dermal progenitor cells originating from the somites.

Experimental manipulation in birds has shown that trunk dermis has a double origin: dorsally, it derives from the somite dermomyotome, while ventrally, it is formed by the somatopleure. Taking advantage of an nlacZ reporter gene integrated into the mouse Msx1 locus (Msx1(nlacZ) allele), we detected segmental expression of the Msx1 gene in cells of the dorsal mesenchyme of the trunk between embryonic days 11 and 14. Replacing somites from a chick host embryo by murine Msx1(nlacZ )somites allowed us to demonstrate that these Msx1-(beta)-galactosidase positive cells are of somitic origin. We propose that these cells are dermal progenitor cells that migrate from the somites and subsequently contribute to the dorsalmost dermis. By analysing Msx1(nlacZ) expression in a Splotch mutant, we observed that migration of these cells does not depend on Pax3, in contrast to other migratory populations such as limb muscle progenitor cells and neural crest cells. Msx1 expression was never detected in cells overlying the dermomyotome, although these cells are also of somitic origin. Therefore, we propose that two somite-derived populations of dermis progenitor cells can be distinguished. Cells expressing the Msx1 gene would migrate from the somite and contribute to the dermis of the dorsalmost trunk region. A second population of cells would disaggregate from the somite and contribute to the dermis overlying the dermomyotome. This population never expresses Msx1. Msx1 expression was investigated in the context of the onset of dermis formation monitored by the Dermo1 gene expression. The gene is downregulated prior to the onset of dermis differentiation, suggesting a role for Msx1 in the control of this process.

The homeobox gene Msx1 is expressed in a subset of somites, and in muscle progenitor cells migrating into the forelimb.

In myoblast cell cultures, the Msx1 protein is able to repress myogenesis and maintain cells in an undifferentiated and proliferative state. However, there has been no evidence that Msx1 is expressed in muscle or its precursors in vivo. Using mice with the nlacZ gene integrated into the Msx1 locus, we show that the reporter gene is expressed in the lateral dermomyotome of brachial and thoracic somites. Cells from this region will subsequently contribute to forelimb and intercostal muscles. Using Pax3 gene transcripts as a marker of limb muscle progenitor cells as they migrate from the somites, we have defined precisely the somitic origin and timing of cell migration from somites to limb buds in the mouse. Differences in the timing of migration between chick and mouse are discussed. Somites that label for Msx1(nlacZ )transgene expression in the forelimb region partially overlap with those that contribute Pax3-expressing cells to the forelimb. In order to see whether Msx1 is expressed in this migrating population, we have grafted somites from the forelimb level of Msx1(nlacZ )mouse embryos into a chick host embryo. We show that most cells migrating into the wing field express the Msx1(nlacZ )transgene, together with Pax3. In these experiments, Msx1 expression in the somite depends on the axial position of the graft. Wing mesenchyme is capable of inducing Msx1 transcription in somites that normally would not express the gene; chick hindlimb mesenchyme, while permissive for this expression, does not induce it. In the mouse limb bud, the Msx1(nlacZ )transgene is downregulated prior to the activation of the Myf5 gene, an early marker of myogenic differentiation. These observations are consistent with the proposal that Msx1 is involved in the repression of muscle differentiation in the lateral half of the somite and in limb muscle progenitor cells during their migration.

Concentration and mobilization of Cd, Cu, Pb and Zn by meiofauna populations living in harbour sediment: their role in the heavy metal flux from sediment to food web.

The bioavailability of Cd, Cu, Pb and Zn was assessed in different harbours of the Atlantic coast (France). The responses of the two dominant meiobenthic groups (nematodes and copepods) to a heavy metal contamination gradient measured in similar subtidal sediments were observed in field surveys. Heavy metal concentrations were measured in nematodes and copepods. Nematodes have higher Cd, Cu, Pb and Zn transfer factors than copepods or other benthic species. The flux of heavy metal through nematodes was estimated and appears to be important compared to plankton in the process of heavy metal transfer to benthic or pelagic food webs.

A poorly differentiated germ cell tumor (seminoma) in a Long Evans rat.

A large neoplasm that replaced 1 testis of a Long Evans Rat was noted at the final necropsy of a dietary 2-yr study. By light microscopy, the morphological features were consistent with a poorly differentiated seminoma. Ultrastructurally, the cells were polygonal, had a round nucleus, had straight cellular boundaries, and bore no resemblance to Sertoli cells. Although there was little evidence of spermatocytic differentiation, the presence of proacrosomal granules and vesicles, prominent Golgi apparatus, tight intercellular junctions, and a few centriolar pairs without axoneme development, in conjunction with the absence of lipid droplets or abundant smooth endoplasmic reticulum, supported the diagnosis of seminoma rather than Leydig cell tumor. The cells were S-100- and vimentin-positive, although cytokeratin- and alpha-fetoprotein-negative. Seminomas are extremely rare neoplasms in rats; this is the first report in this strain and the first extensive analysis of a rat seminoma without spermatocytic differentiation.

Acetylcholine receptor formation in mouse-chick chimera.

This study investigated possible interactions between motoneurons and somitic-derived muscle cells in the formation of neuromuscular synapses in the myotome. The peculiarities of the neuromuscular synaptic pattern in chick and mouse embryos provided a model for studying the achievement of synaptogenesis between chick motoneurons and mouse muscle cells. In chick embryo, initial AChR clustering occurs well before innervation of the myotome, whereas in mouse embryo nerve axons invade the myotome extensively before the appearance of AChR clusters. Our approach was to replace somites from a chick host embryo with those derived from mouse donor embryos. We show that muscle cells from mouse myotome can differentiate in the chick embryo environment and form neuromuscular contacts with chick motor axons. Host axons invaded in ovo differentiating mouse myotome at a time when they had not yet reached the host myotome. This particular ingrowth of motor nerves was attributable to the mouse transplant since use of a quail somite did not produce the same effect as the mouse somite, which suggests that developing mouse muscles specifically modify the time course of chick axogenesis. The synaptic areas formed between chick motor axons and mouse myotubes developed according to the mouse pattern. Both the timing of their appearance and their morphology correlated perfectly with events in mouse synaptogenesis. These results indicate the important role played by postsynaptic membrane in controlling the first steps of AChR formation.

Activity levels and the relationship to lung function and nutritional status in children with cystic fibrosis.

Cystic fibrosis is characterized by chronic obstructive lung disease and malnutrition. Previous studies have shown that nutritional status and lung function are limiting factors for exercise capacity. A reduced exercise capacity may in turn diminish activity levels. We evaluated whether the total time spent somewhat active (e.g., walking) or active (e.g., biking), as reported by the Habitual Activity Estimation Scale, was related to lung function, as evaluated by forced expiratory volume in one second (%predicted FEV1), and nutritional status, measured as body mass percentile, in 36 children with cystic fibrosis, aged 6 to 16 years. The Habitual Activity Estimation Scale questionnaires were completed by the parents for children younger than 12 years of age and by both the parent and the child, independently, for those 12 years and older. Patients had a body mass percentile of 99 +/- 15.2% and % predicted FEV1 of 85.7 +/- 20, with no differences between boys (15/36) and girls (21/36). Boys spent 8.1 hours and girls spent 7.5 hours (P > 0.1) being at least somewhat active. These values are similar to those reported for healthy boys and girls. In patients with significant lung disease (%predicted FEV1, < or = 75; n = 11), activity level (the time spent somewhat active or active) was related to nutritional status (r = 0.675; P = 0.02) but not to lung function (r = 0.21; P > 0.1). Activity level reported by patients 12 years of age and older was on average 24.1% higher (P < 0.05) than that reported by their parents, but the two reportings were related (r = 0.758; P = 0.004). These results suggest that activity level may be restricted by nutritional status in those patients with significant air flow limitation. We suggest that improving the nutritional status of cystic fibrosis patients may prevent decreases in activity levels and quality of life of these affected children.

Restricted use of cationic germline V(H) gene segments in human Rh(D) red cell antibodies.

The human red cell Rh(D) antigen elicits the production of high-affinity IgG antibodies, which can prevent blood transfusion and cause hemolytic disease of the newborn. It has been known for 20 years that Rh(D) antibodies are among the most positively charged human serum IgGs. Analysis by IEF of 9 human anti-Rh(D) monoclonal antibodies showed that their isoelectric points (pI) (8.3 to 8.6) were also significantly higher than the average pI of serum IgGs (7.0 to 8.5). Sequencing of the anti-Rh(D) H and L chains cDNAs showed a preferential use of V(H)1, V(H)3, J(H)6, and V(kappa)1 gene segments. The high pIs in IEF were correlated with a higher number of cationic amino acid residues in the H chain V regions without clustering in the complementary determining region. Computer analysis indicated that the germline V(H) used in anti-Rh(D) was selected among the most cationic segments available in the human V(H) repertoire or expressed in normal B cells. These results indicate that the selection of cationic V(H) segments may be an important early step in the formation of clinically relevant anti-Rh(D) and other red cell antibodies, possibly to facilitate epitope binding in the negatively charged red cell membrane environment.

Neural tube can induce fast myosin heavy chain isoform expression during embryonic development.

We investigated the role of the neural tube in muscle cell differentiation in developing somitic myotome of chick embryo, particularly through fast myosin heavy chain (MHC) isoform expression. An embryonic fast MHC labeled with EB165 mAb was expressed in somitic cells from stage 15 of Hamburger and Hamilton (H.H.) (24 somites). Moreover, a distinct early embryonic fast MHC was expressed only from stage 15 of H.H. to stage 36 (E10). Like neonatal MHC, this isoform was labeled with 2E9 mAb but differed in its immunopeptide mapping. Expression of EB165-labeled embryonic fast MHC occurred in somitic myotomes deprived of neural tube influence by in ovo ablation as well as in somite explants cultured alone in vitro. Conversely, ablation of the neural tube prevented somitic expression of MHC labeled with 2E9 mAb. The neural tube induced in vitro expression of this MHC in explants of somites which failed to express it when cultured alone. These results indicate that signals emanating from the neural tube are required for the expression of early embryonic fast MHC isoform in developing somitic myotome.

Differentiation potentialities of distinct myogenic cell precursors in avian embryos.

Interspecific grafting experiments between chick and quail embryos were carried out to investigate the differentiation capacities of myoblasts from different development stages. Grafts consisted of 3.5-day-old embryonic quail dermomyotomes isolated from the cranial level, 7- to 10-day-old and 16-day-old embryonic quail pectoralis muscles, 15-day-old postnatal quail pectoralis muscle, and 3- to 10-day-old embryonic quail cardiac and gut muscles. Grafts were implanted into 2-day-old chick embryos in place of the dorsal halves of somites from the prospective wing level. After implantation of dermomyotome fragments, we observed that quail cells participated in trunk and limb musculature. After implantation of 7- to 10-day-old embryonic muscle, quail cells were rarely found in the limb but systematically took part in the formation of trunk muscles. All these capacities were totally lost in 16-day-old embryonic and 15-day-old postnatal muscles. After implantation of nonsomitic derivatives such as embryonic cardiac and gut muscles, implanted cells never participated either in wing or trunk musculature. After dermomyotome, embryonic muscle, and gut implantation, quail cells were capable of invading the dermis and aggregating into feather germs. Our results extend those previously reported and indicate that somitic myogenic derivatives which do not migrate in the normal course of embryogenesis have migratory potentialities and are able to give rise to axial muscles. All these potentialities are lost as myogenesis proceeds in embryos.

Use of hu-IgG-SCID mice to evaluate the in vivo stability of human monoclonal IgG antibodies.

Human and in vitro modified mAbs such as humanized rodent mAbs and immunotoxins are now considered for a variety of applications in humans. The adequate in vivo stability of these Ig preparations is not easily predicted from in vitro studies and may be essential for many therapeutic applications. In this study, we report the development and characterization of an in vivo model for testing this parameter using SCID mice containing a physiological concentration of human IgG (hu-IgG-SCID). The model was tested with several IgG1 and IgG3 human mAbs reacting with the human Rh(D) red cell antigen. It is known that human IgG have a shorter half-life in SCID mice than in humans. However, our results showed that the half-life of IgG3 mAbs (1.5 +/- 0.5 days) was much shorter than the one of IgG1 mAbs (5.8 +/- 1.4 days), indicating that the relative stability of IgG1 and IgG3 human mAbs in hu-IgG-SCID mice is similar to the one previously reported in humans (21 days vs. 7 days respectively). The IgG catabolism rate in humans is known to be inversely proportional to serum IgG concentrations. Accordingly, the dilution of the mAbs in a large excess (200-fold) of human IgG was found to be an important parameter of the hu-IgG-SCID mouse model since much longer (3-4-fold) mAb half-lives were obtained in the presence of a lower dose or in the absence of co-injected human IgG. This study show the usefulness of this animal model for the evaluation of human antibody stability in an in vivo environment.