Growth of donor-derived dendritic cells from the bone marrow of murine liver auograft recipients in response to granulocyte/macrophage colony-stimulating factor

Allografts of the liver, which has a comparatively heavy leukocyte content compared with other vascularized organs, are accepted permanently across major histocompatibility complex barriers in many murine strain combinations without immunosuppressive therapy. It has been postulated that this inherent tolerogenicity of the liver may be a consequence of the migration and perpetuation within host lymphoid tissues of potentially tolerogenic donor-derived ("chimeric") leukocytes, in particular, the precursors of chimeric dendritic cells (DC). In this study, we have used granulocyte/macrophage colony-stimulating factor to induce the propagation of progenitors that give rise to DC (CD45+, CDllc+, 33D1+, nonlymphoid dendritic cell 145 +, major histocompatibility complex class II+, B7-1+) in li-tuid cultures of murine bone marrow cells. Using this technique, together with immunocytochemical and molecular methods, we show that, in addition to cells expressing female host (C3H) phenotype (H-2Kk+; I-E+; Y chromosome-), a minor population of male donor (B10)-derived cells (H-2Kb+; I-A+; Y chromosome+) can also be grown in 10-d DC cultures from the bone marrow of liver allograft recipients 14 d after transplant. Highly purified nonlymphoid dendritic cell 145+ DC sorted from these bone marrow-derived cell cultures were shown to comprise ~1-10% cells of donor origin (Y chromosome +) by polymerase chain reaction analysis. In addition, sorted DC stimulated naive, recipient strain T lymphocytes in primary mixed leukocyte cultures. Evidence was also obtained for the growth of donor-derived cells from the spleen but not the thymus. In contrast, donor ceils could not be propagated from the bone marrow or other lymphoid tissues of nonimmunosuppressed C3H mice rejecting cardiac allografrs from the same donor strain (B10). These findings provide a basis for the establishment and perpetuation of cell chimerism after organ transplantation. © 1995, Rockefeller University Press., All rights reserved

Stability, resolution, and ultra-low wear amplitude modulation atomic force microscopy of DNA: Small amplitude small set-point imaging

A way to operate fundamental mode amplitude modulation atomic force microscopy is introduced which optimizes stability and resolution for a given tip size and shows negligible tip wear over extended time periods (∼24 h). In small amplitude small set-point (SASS) imaging, the cantilever oscillates with sub-nanometer amplitudes in the proximity of the sample, without the requirement of using large drive forces, as the dynamics smoothly lead the tip to the surface through the water layer. SASS is demonstrated on single molecules of double-stranded DNA in ambient conditions where sharp silicon tips (R ∼ 2-5 nm) can resolve the right-handed double helix

Spin polarization versus lifetime effects at point contacts between superconducting niobium and normal metals

Point-contact Andreev reflection spectroscopy is used to measure the spin polarization of metals but analysis of the spectra has encountered a number of serious challenges, one of which is the difficulty to distinguish the effects of spin polarization from those of the finite lifetime of Cooper pairs. We have recently confirmed the polarization-lifetime ambiguity for Nb-Co and Nb-Cu contacts and suggested to use Fermi surface mismatch, the normal reflection due to the difference of Fermi wave vectors of the two electrodes, to solve this dilemma. Here we present further experiments on contacts between superconducting Nb and the ferromagnets Fe and Ni as well as the noble metals Ag and Pt that support our previous results. Our data indicate that the Nb - normal metal interfaces have a transparency of up to about 80 per cent and a small, if not negligible, spin polarization.Comment: 7 pages, 2 figures, submitted to Proceedings of the 26th Conference on Low Temperature Physic

Does shear wave ultrasound independently predict axillary lymph node metastasis in women with invasive breast cancer?

Shear wave elastography (SWE) shows promise as an adjunct to greyscale ultrasound examination in assessing breast masses. In breast cancer, higher lesion stiffness on SWE has been shown to be associated with features of poor prognosis. The purpose of this study was to assess whether lesion stiffness at SWE is an independent predictor of lymph node involvement. Patients with invasive breast cancer treated by primary surgery, who had undergone SWE examination were eligible. Data were retrospectively analysed from 396 consecutive patients. The mean stiffness values were obtained using the Aixplorer(®) ultrasound machine from SuperSonic Imagine Ltd. Measurements were taken from a region of interest positioned over the stiffest part of the abnormality. The average of the mean stiffness value obtained from each of two orthogonal image planes was used for analysis. Associations between lymph node involvement and mean lesion stiffness, invasive cancer size, histologic grade, tumour type, ER expression, HER-2 status and vascular invasion were assessed using univariate and multivariate logistic regression. At univariate analysis, invasive size, histologic grade, HER-2 status, vascular invasion, tumour type and mean stiffness were significantly associated with nodal involvement. Nodal involvement rates ranged from 7 % for tumours with mean stiffness <50 kPa to 41 % for tumours with a mean stiffness of >150 kPa. At multivariate analysis, invasive size, tumour type, vascular invasion, and mean stiffness maintained independent significance. Mean stiffness at SWE is an independent predictor of lymph node metastasis and thus can confer prognostic information additional to that provided by conventional preoperative tumour assessment and staging

Target product profiles for protecting against outdoor malaria transmission.

BACKGROUND\ud \ud Long-lasting insecticidal nets (LLINs) and indoor residual sprays (IRS) have decimated malaria transmission by killing indoor-feeding mosquitoes. However, complete elimination of malaria transmission with these proven methods is confounded by vectors that evade pesticide contact by feeding outdoors.\ud \ud METHODS\ud \ud For any assumed level of indoor coverage and personal protective efficacy with insecticidal products, process-explicit malaria transmission models suggest that insecticides that repel mosquitoes will achieve less impact upon transmission than those that kill them outright. Here such models are extended to explore how outdoor use of products containing either contact toxins or spatial repellents might augment or attenuate impact of high indoor coverage of LLINs relying primarily upon contact toxicity.\ud \ud RESULTS\ud \ud LLIN impact could be dramatically enhanced by high coverage with spatial repellents conferring near-complete personal protection, but only if combined indoor use of both measures can be avoided where vectors persist that prefer feeding indoors upon humans. While very high levels of coverage and efficacy will be required for spatial repellents to substantially augment the impact of LLINs or IRS, these ambitious targets may well be at least as practically achievable as the lower requirements for equivalent impact using contact insecticides.\ud \ud CONCLUSIONS\ud \ud Vapour-phase repellents may be more acceptable, practical and effective than contact insecticides for preventing outdoor malaria transmission because they need not be applied to skin or clothing and may protect multiple occupants of spaces outside of treatable structures such as nets or houses

Patchiness of ion-exchanged mica revealed by DNA binding dynamics at short length scales

The binding of double-stranded (ds) DNA to mica can be controlled through ion-exchanging the mica with divalent cations. Measurements of the end-to-end distance of linear DNA molecules discriminate whether the binding mechanism occurs through 2D surface equilibration or kinetic trapping. A range of linear dsDNA fragments have been used to investigate length dependences of binding. Mica, ion-exchanged with Ni(II) usually gives rise to kinetically trapped DNA molecules, however, short linear fragments (<800 bp) are seen to deviate from the expected behaviour. This indicates that ion-exchanged mica is heterogeneous, and contains patches or domains, separating different ionic species. These results correlate with imaging of dsDNA under aqueous buffer on Ni(II)-mica and indicate that binding domains are of the order of 100 nm in diameter. Shorter DNA fragments behave intermediate to the two extreme cases of 2D equilibration and kinetic trapping. Increasing the incubation time of Ni(II) on mica, from minutes to hours, brings the conformations of the shorter DNA fragments closer to the theoretical value for kinetic trapping, indicating that long timescale kinetics play a role in ion-exchange. X-ray photoelectron spectroscopy (XPS) was used to confirm that the relative abundance of Ni(II) ions on the mica surface increases with time. These findings can be used to enhance spatial control of binding of DNA to inorganic surfaces with a view to patterning high densities arrays

Explanation and elaboration of the SQUIRE (Standards for Quality Improvement Reporting Excellence) Guidelines, V.2.0: examples of SQUIRE elements in the healthcare improvement literature

Since its publication in 2008, SQUIRE (Standards for Quality Improvement Reporting Excellence) has contributed to the completeness and transparency of reporting of quality improvement work, providing guidance to authors and reviewers of reports on healthcare improvement work. In the interim, enormous growth has occurred in understanding factors that influence the success, and failure, of healthcare improvement efforts. Progress has been particularly strong in three areas: the understanding of the theoretical basis for improvement work; the impact of contextual factors on outcomes; and the development of methodologies for studying improvement work. Consequently, there is now a need to revise the original publication guidelines. To reflect the breadth of knowledge and experience in the field, we solicited input from a wide variety of authors, editors and improvement professionals during the guideline revision process. This Explanation and Elaboration document (E&E) is a companion to the revised SQUIRE guidelines, SQUIRE 2.0. The product of collaboration by an international and interprofessional group of authors, this document provides examples from the published literature, and an explanation of how each reflects the intent of a specific item in SQUIRE. The purpose of the guidelines is to assist authors in writing clearly, precisely and completely about systematic efforts to improve the quality, safety and value of healthcare services. Authors can explore the SQUIRE statement, this E&E and related documents in detail at http://www.squire-statement.org

Suv4-20h Histone Methyltransferases Promote Neuroectodermal Differentiation by Silencing the Pluripotency-Associated Oct-25 Gene

Post-translational modifications (PTMs) of histones exert fundamental roles in regulating gene expression. During development, groups of PTMs are constrained by unknown mechanisms into combinatorial patterns, which facilitate transitions from uncommitted embryonic cells into differentiated somatic cell lineages. Repressive histone modifications such as H3K9me3 or H3K27me3 have been investigated in detail, but the role of H4K20me3 in development is currently unknown. Here we show that Xenopus laevis Suv4-20h1 and h2 histone methyltransferases (HMTases) are essential for induction and differentiation of the neuroectoderm. Morpholino-mediated knockdown of the two HMTases leads to a selective and specific downregulation of genes controlling neural induction, thereby effectively blocking differentiation of the neuroectoderm. Global transcriptome analysis supports the notion that these effects arise from the transcriptional deregulation of specific genes rather than widespread, pleiotropic effects. Interestingly, morphant embryos fail to repress the Oct4-related Xenopus gene Oct-25. We validate Oct-25 as a direct target of xSu4-20h enzyme mediated gene repression, showing by chromatin immunoprecipitaton that it is decorated with the H4K20me3 mark downstream of the promoter in normal, but not in double-morphant, embryos. Since knockdown of Oct-25 protein significantly rescues the neural differentiation defect in xSuv4-20h double-morphant embryos, we conclude that the epistatic relationship between Suv4-20h enzymes and Oct-25 controls the transit from pluripotent to differentiation-competent neural cells. Consistent with these results in Xenopus, murine Suv4-20h1/h2 double-knockout embryonic stem (DKO ES) cells exhibit increased Oct4 protein levels before and during EB formation, and reveal a compromised and biased capacity for in vitro differentiation, when compared to normal ES cells. Together, these results suggest a regulatory mechanism, conserved between amphibians and mammals, in which H4K20me3-dependent restriction of specific POU-V genes directs cell fate decisions, when embryonic cells exit the pluripotent state