Susceptibility induced gray–white matter MRI contrast in the human brain

AbstractMR phase images have shown significantly improved contrast between cortical gray and white matter regions compared to magnitude images obtained with gradient echo sequences. A variety of underlying biophysical mechanisms (including iron, blood, myelin content, macromolecular chemical exchange, and fiber orientation) have been suggested to account for this observation but assessing the individual contribution of these factors is limited in vivo.For a closer investigation of iron and myelin induced susceptibility changes, postmortem MRI of six human corpses (age range at death: 56–80years) was acquired in situ. Following autopsy, the iron concentrations in the frontal and occipital cortex as well as in white matter regions were chemically determined. The magnetization transfer ratio (MTR) was used as an indirect measure for myelin content. Susceptibility effects were assessed separately by determining R2* relaxation rates and quantitative phase shifts. Contributions of myelin and iron to local variations of the susceptibility were assessed by univariate and multivariate linear regression analysis.Mean iron concentration was lower in the frontal cortex than in frontal white matter (26±6 vs. 45±6mg/kg wet tissue) while an inverse relation was found in the occipital lobe (cortical gray matter: 41±10 vs. white matter: 34±10mg/kg wet tissue). Multiple regression analysis revealed iron and MTR as independent predictors of the effective transverse relaxation rate R2* but solely MTR was identified as source of MR phase contrast. R2* was correlated with iron concentrations in cortical gray matter only (r=0.42, p<0.05).In conclusion, MR phase contrast between cortical gray and white matter can be mainly attributed to variations in myelin content, but not to iron concentration. Both, myelin and iron impact the effective transverse relaxation rate R2* significantly. Magnitude contrast is limited because it only reflects the extent but not the direction of the susceptibility shift

Roll-coating fabrication of flexible organic solar cells: comparison of fullerene and fullerene-free systems

Flexible organic solar cells (OSCs) based on a blend of low-bandgap polymer donor PTB7-TH and non-fullerene small molecule acceptor IEIC were fabricated via a roll-coating process under ambient atmosphere. Both an indium tin oxide (ITO)-free substrate and a flexible ITO substrate were employed in these inverted OSCs. OSCs with flexible ITO and ITO-free substrates exhibited power conversion efficiencies (PCEs) up to 2.26% and 1.79%, respectively, which were comparable to those of the reference devices based on fullerene acceptors under the same conditions. This is the first example for all roll-coating fabrication procedures for flexible OSCs based on non-fullerene acceptors with the PCE exceeding 2%. The fullerene-free OSCs exhibited better dark storage stability than the fullerene-based control devices.NSFC [91433114, 51261130582, 21025418]; Danish National Research FoundationSCI(E)[email protected]; [email protected]

Gender comparison of clinical, histopathological, therapeutic and outcome factors in 185,967 colon cancer patients

Introduction: Colorectal carcinomas represent the third most common cause of cancer-related deaths in Germany. Although the incidence is significantly higher in men compared with women and gender is a well-established crucial factor for outcome in other diseases, detailed gender comparisons for colon cancer are lacking. Methods: This retrospective population-based cohort study included all patients diagnosed with colon cancer in Germany between 2000 and 2016 who were included in the common dataset of colorectal cancer patients from the quality conference of the German Cancer Society. We compared clinical, histopathological, and therapeutic characteristics as well as overall and recurrence-free survival. Results: A total of 185,967 patients were included in the study, of which 85,685 were female (46.1%) and 100,282 were male (53.9%). The proportion of women diagnosed with colon cancer decreased from 2000 to 2016 (f: 26.6 to 40.1%; m: 24.9 to 41.9%; p < 0.001), and the proportion of very old patients was especially high in women (f: 27.3%; m: 15.6%; p < 0.001). The localization in women was more right-sided (f: 45.0%, m: 36.7%; p < 0.001), and women had a higher tumor grading and a higher UICC stage (especially stage III nodal-positive) at diagnosis of primary colon cancer (UICC III: f: 22.7%, m: 21.0%; p < 0.001). We could detect a significantly better overall (hazard ratio: 0.853, lower 95%: 0.841, upper 95%: 0.864; p < 0.001) and recurrence-free survival (hazard ratio: 0.857, lower 95%: 0.845, upper 95%: 0.868; p < 0.001) in women compared with men, even though women received chemotherapy less frequently compared with men (f: 26.1%, m: 28.1%; p < 0.001). Conclusion: We could detect several variables that differed significantly between men and women regarding clinical, histopathological, therapeutic, and outcome factors. We believe that it is crucial to consider gender as a key factor in the diagnosis and treatment of colon cancer. Sex-specific diagnostic tools could lead to an earlier diagnosis of colon cancer in women, and ways to increase the rate of chemotherapy in women should be evaluated. Furthermore, we recommend stratifying randomized trials by gender

Cell-cell interactome of the hematopoietic niche and its changes in acute myeloid leukemia.

The bone marrow (BM) is a complex microenvironment, coordinating the production of billions of blood cells every day. Despite its essential role and its relevance to hematopoietic diseases, this environment remains poorly characterized. Here we present a high-resolution characterization of the niche in health and acute myeloid leukemia (AML) by establishing a single-cell gene expression database of 339,381 BM cells. We found significant changes in cell type proportions and gene expression in AML, indicating that the entire niche is disrupted. We then predicted interactions between hematopoietic stem and progenitor cells (HSPCs) and other BM cell types, revealing a remarkable expansion of predicted interactions in AML that promote HSPC-cell adhesion, immunosuppression, and cytokine signaling. In particular, predicted interactions involving transforming growth factor β1 (TGFB1) become widespread, and we show that this can drive AML cell quiescence in vitro. Our results highlight potential mechanisms of enhanced AML-HSPC competitiveness and a skewed microenvironment, fostering AML growth

Quantitative susceptibility mapping (QSM) as a means to measure brain iron? A post mortem validation study

AbstractQuantitative susceptibility mapping (QSM) is a novel technique which allows determining the bulk magnetic susceptibility distribution of tissue in vivo from gradient echo magnetic resonance phase images. It is commonly assumed that paramagnetic iron is the predominant source of susceptibility variations in gray matter as many studies have reported a reasonable correlation of magnetic susceptibility with brain iron concentrations in vivo. Instead of performing direct comparisons, however, all these studies used the putative iron concentrations reported in the hallmark study by Hallgren and Sourander (1958) for their analysis. Consequently, the extent to which QSM can serve to reliably assess brain iron levels is not yet fully clear. To provide such information we investigated the relation between bulk tissue magnetic susceptibility and brain iron concentration in unfixed (in situ) post mortem brains of 13 subjects using MRI and inductively coupled plasma mass spectrometry. A strong linear correlation between chemically determined iron concentration and bulk magnetic susceptibility was found in gray matter structures (r=0.84, p<0.001), whereas the correlation coefficient was much lower in white matter (r=0.27, p<0.001). The slope of the overall linear correlation was consistent with theoretical considerations of the magnetism of ferritin supporting that most of the iron in the brain is bound to ferritin proteins. In conclusion, iron is the dominant source of magnetic susceptibility in deep gray matter and can be assessed with QSM. In white matter regions the estimation of iron concentrations by QSM is less accurate and more complex because the counteracting contribution from diamagnetic myelinated neuronal fibers confounds the interpretation

A Nanoparticle Approach towards Morphology Controlled Organic Photovoltaics (OPV)

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Commitment to the Regulatory T Cell Lineage Requires CARMA1 in the Thymus but Not in the Periphery

Regulatory T (Treg) cells expressing forkhead box P3 (Foxp3) arise during thymic selection among thymocytes with modestly self-reactive T cell receptors. In vitro studies suggest Foxp3 can also be induced among peripheral CD4+ T cells in a cytokine dependent manner. Treg cells of thymic or peripheral origin may serve different functions in vivo, but both populations are phenotypically indistinguishable in wild-type mice. Here we show that mice with a Carma1 point mutation lack thymic CD4+Foxp3+ Treg cells and demonstrate a cell-intrinsic requirement for CARMA1 in thymic Foxp3 induction. However, peripheral Carma1-deficient Treg cells could be generated and expanded in vitro in response to the cytokines transforming growth factor beta (TGFβ) and interleukin-2 (IL-2). In vivo, a small peripheral Treg pool existed that was enriched at mucosal sites and could expand systemically after infection with mouse cytomegalovirus (MCMV). Our data provide genetic evidence for two distinct mechanisms controlling regulatory T cell lineage commitment. Furthermore, we show that peripheral Treg cells are a dynamic population that may expand to limit immunopathology or promote chronic infection