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.

A protein-truncating R179X variant in RNF186 confers protection against ulcerative colitis

Protein-truncating variants protective against human disease provide in vivo validation of therapeutic targets. Here we used targeted sequencing to conduct a search for protein-truncating variants conferring protection against inflammatory bowel disease exploiting knowledge of common variants associated with the same disease. Through replication genotyping and imputation we found that a predicted protein-truncating variant (rs36095412, p.R179X, genotyped in 11,148 ulcerative colitis patients and 295,446 controls, MAF=up to 0.78%) in RNF186, a single-exon ring finger E3 ligase with strong colonic expression, protects against ulcerative colitis (overall P=6.89 × 10(-7), odds ratio=0.30). We further demonstrate that the truncated protein exhibits reduced expression and altered subcellular localization, suggesting the protective mechanism may reside in the loss of an interaction or function via mislocalization and/or loss of an essential transmembrane domain.

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

Transforming growth factor-β (TGF-β) maintains self-tolerance through a constitutive inhibitory effect on T-cell reactivity. In most physiological situations, the tolerogenic effects of TGF-β depend on the canonical signaling molecule Smad3. To characterize how TGF-β/Smad3 signaling contributes to maintenance of T-cell tolerance, we characterized the transcriptional landscape downstream of TGF-β/Smad3 signaling in resting or activated CD4 T cells. We report that in the presence of TGF-β, 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-β biology and identified both known and putative immunoregulatory genes. Moreover, we provide genomic and functional evidence that the TGF-β/Smad3 pathway regulates T-cell activation and metabolism. In particular, we show that TGF-β/Smad3 signaling dampens the effect of CD28 stimulation on T-cell growth and proliferation. The impact of TGF-β/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-β-Smad3 signaling may maintain T-cell tolerance by suppressing co-stimulation-dependent mobilization of anabolic pathways.

[Direct supervision. Perceptions of ex-residents in family medicine]

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.

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.

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.

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.