Significant difference between three observers in the assessment of intraepidermal nerve fiber density in skin biopsy

<p>Abstract</p> <p>Background</p> <p>The determination of Intraepidermal Nerve Fiber Density (IENFD) in skin biopsy is a useful method for the evaluation of different types of peripheral neuropathies. To allow a reliable use of the method it is necessary to determine interobserver reliability. Previous studies dealing with this topic used limited suitable statistical methods.</p> <p>Methods</p> <p>In the present study three observers determined the IENFD and estimated the staining quality of the basement membrane for an adequate quantity of 120 skin biopsies (stained with indirect immunofluorescence technique) from 68 patients. More adequate statistical methods like intraclass correlation coefficient and Bland Altman Plot were chosen to estimate interobserver reliability.</p> <p>Results</p> <p>We found an unexpected significant difference in IENFD between the observers (p < 0.05) and so the results of this study are not in line with the high interobserver reliability reported before (intraclass correlation coefficient: 0.73). The Bland Altmann Plot showed a variance growing with rising mean. The difference in IENFD between the observers and the resulting low interobserver reliability is likely caused by different interpretations of the standard counting rules. There was no significant difference in IENFD between observers for biopsies with a well-defined basement membrane. Thus skin biopsies with an inexactly defined basement membrane should not be used diagnostically for the determination of IENFD.</p> <p>Conclusion</p> <p>These results emphasise that standardisation of the method is extremely important and at least two observers should analyse skin biopsies with critical IENFD near the cut-off values.</p

Protein Kinase D regulates several aspects of development in Drosophila melanogaster

<p>Abstract</p> <p>Background</p> <p>Protein Kinase D (PKD) is an effector of diacylglycerol-regulated signaling pathways. Three isoforms are known in mammals that have been linked to diverse cellular functions including regulation of cell proliferation, differentiation, motility and secretory transport from the trans-Golgi network to the plasma membrane. In <it>Drosophila</it>, there is a single PKD orthologue, whose broad expression implicates a more general role in development.</p> <p>Results</p> <p>We have employed tissue specific overexpression of various PKD variants as well as tissue specific RNAi, in order to investigate the function of the PKD gene in <it>Drosophila</it>. Apart from a wild type (WT), a kinase dead (kd) and constitutively active (SE) <it>Drosophila </it>PKD variant, we also analyzed two human isoforms hPKD2 and hPKD3 for their capacity to substitute PKD activity in the fly. Overexpression of either WT or kd-PKD variants affected primarily wing vein development. However, overexpression of SE-PKD and PKD RNAi was deleterious. We observed tissue loss, wing defects and degeneration of the retina. The latter phenotype conforms to a role of PKD in the regulation of cytoskeletal dynamics. Strongest phenotypes were larval to pupal lethality. RNAi induced phenotypes could be rescued by a concurrent overexpression of <it>Drosophila </it>wild type PKD or either human isoform hPKD2 and hPKD3.</p> <p>Conclusion</p> <p>Our data confirm the hypothesis that <it>Drosophila </it>PKD is a multifunctional kinase involved in diverse processes such as regulation of the cytoskeleton, cell proliferation and death as well as differentiation of various fly tissues.</p

Homogeneous conversion of NOx_{x} and NH3_{3} with CH4_{4}, CO, and C2_{2}H4_{4} at the diluted conditions of exhaust-gases of lean operated natural gas engines

Understanding gas‐phase reactions in model gas mixtures approximating pre‐turbine heavy‐duty natural gas engine exhaust compositions containing NO, NH$_{3}$, NO$_{2}$, CH$_{4}$, CO, and C$_{2}$H$_{4}$ is extremely relevant for aftertreatment procedure and catalyst design and is thus addressed in this work. In a plug‐flow reactor at atmospheric pressure, five different model gas mixtures were investigated in the temperature range of 700‐1 200 K, using species analysis with electron ionization molecular‐beam mass spectrometry. The mixtures were designed to reveal influences of individual components by adding NO$_{2}$, CH$_{4}$, CO, and C$_{2}$H$_{4}$ sequentially to a highly argon‐diluted NO/NH$_{3}$ base mixture. Effects of all components on the reactivity for NO$_{x}$ conversion were investigated both experimentally as well as by comparison with three selected kinetic models. Main results show a significantly increased reactivity upon NO$_{2}$ and hydrocarbon addition with lowered NO conversion temperatures by up to 200 K. Methane was seen to be of dominant influence in the carbon‐containing mixtures regarding interactions between the carbon and nitrogen chemistry as well as formaldehyde formation. The three tested mechanisms were capable to overall represent the reaction behavior satisfactorily. On this basis, it can be stated that significant gas‐phase reactivity was observed among typical constituents of pre‐turbine natural gas engine exhaust at moderate temperature

Serum glial fibrillary acidic protein and neurofilament light chain in patients with early treated phenylketonuria

To pave the way for healthy aging in early treated phenylketonuria (ETPKU) patients, a better understanding of the neurological course in this population is needed, requiring easy accessible biomarkers to monitor neurological disease progression in large cohorts. The objective of this pilot study was to investigate the potential of glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) as blood biomarkers to indicate changes of the central nervous system in ETPKU. In this single-center cross-sectional study, GFAP and NfL concentrations in serum were quantified using the Simoa® multiplex technology in 56 ETPKU patients aged 6–36 years and 16 age matched healthy controls. Correlation analysis and hierarchical linear regression analysis were performed to investigate an association with disease-related biochemical parameters and retinal layers assessed by optical coherence tomography. ETPKU patients did not show significantly higher GFAP concentrations (mean 73 pg/ml) compared to healthy controls (mean 60 pg/ml, p = 0.140). However, individual pediatric and adult ETPKU patients had GFAP concentrations above the healthy control range. In addition, there was a significant association of GFAP concentrations with current plasma tyrosine concentrations (r = −0.482, p = 0.036), a biochemical marker in phenylketonuria, and the retinal inner nuclear layer volume (r = 0.451, p = 0.04). There was no evidence of NfL alterations in our ETPKU cohort. These pilot results encourage multicenter longitudinal studies to further investigate serum GFAP as a complementary tool to better understand and monitor neurological disease progression in ETPKU. Follow-up investigations on aging ETPKU patients are required to elucidate the potential of serum NfL as biomarker

Self-immobilizing Biocatalysts for fluidic Reaction Cascades

The industrial implementation of whole-cells and enzymes in flow biocatalysis microreactors is essential for the emergence of a biobased circular economy. Major challenges concern the efficient immobilization of delicate enzymes inside miniaturized reactors without compromising their catalytic activity. We describe the design and application of four different immobilization techniques including self-immobilizing whole-cells and purified enzymes on magnetic microbeads, as well as reactor modules manufactured by 3D printing of bioinks containing thermostable enzymes. To increase the volumetric activity of our microreactors we furthermore developed and applied self-assembling all-enzyme hydrogels with cofactor-regenerating capabilities. The resulting reactor formats have excellent operational stability times of > 14 days and maximum space-time yields of > 450 g product/L-1day-1 paving the way for mild and effective immobilization techniques of biocatalysts in microfluidic systems

atTRACTive: Semi-automatic white matter tract segmentation using active learning

Accurately identifying white matter tracts in medical images is essential for various applications, including surgery planning and tract-specific analysis. Supervised machine learning models have reached state-of-the-art solving this task automatically. However, these models are primarily trained on healthy subjects and struggle with strong anatomical aberrations, e.g. caused by brain tumors. This limitation makes them unsuitable for tasks such as preoperative planning, wherefore time-consuming and challenging manual delineation of the target tract is typically employed. We propose semi-automatic entropy-based active learning for quick and intuitive segmentation of white matter tracts from whole-brain tractography consisting of millions of streamlines. The method is evaluated on 21 openly available healthy subjects from the Human Connectome Project and an internal dataset of ten neurosurgical cases. With only a few annotations, the proposed approach enables segmenting tracts on tumor cases comparable to healthy subjects (dice=0.71), while the performance of automatic methods, like TractSeg dropped substantially (dice=0.34) in comparison to healthy subjects. The method is implemented as a prototype named atTRACTive in the freely available software MITK Diffusion. Manual experiments on tumor data showed higher efficiency due to lower segmentation times compared to traditional ROI-based segmentation

Exploring the interaction kinetics of butene isomers and NOx_{x} at low temperatures and diluted conditions

The oxidation of 1-butene and i-butene with and without addition of 1000 ppm NO was experimentally and numerically studied primarily at fuel-rich (ϕ = 2.0) conditions under high dilution (96% Ar) in a flow reactor operated at atmospheric pressure in the low temperature range of approximately 600-1200 K. Numerous intermediate species were detected and quantified using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). An elementary-step reaction mechanism consisting of 3996 reactions among 682 species, based on literature and this work, was established to describe the reactions and interaction kinetics of the butene isomers with oxygen and nitrogenous components. Model predictions were compared with the experimental results to gain insight into the low- and high-temperature fuel consumption without and with NO addition and thus the respective interaction chemistry. This investigation firstly contributes a consistent set of temperature-dependent concentration profiles for these two butene isomers under conditions relevant for engine exhaust gases. Secondly, the observed oxidation kinetics is significantly altered with the addition of NO. Specifically, NO promotes fuel consumption and introduces for i-butene a low-temperature behavior featuring a negative temperature coefficient (NTC) region. The present model shows reasonable agreement with the experimental results for major products and intermediate species, and it is capable to explain the promoting effect of NO that is initiated by its contribution to the radical pool. Further, it can describe the observed NTC region for the i-butene/NO mixture as a result of the competition of chain propagation and chain terminating reactions that were identified by reaction flow and sensitivity analyses

A Magnetosome-Based Platform for Flow Biocatalysis

Biocatalysis in flow reactor systems is of increasing importance for the transformation of the chemical industry. However, the necessary immobilization of biocatalysts remains a challenge. We here demonstrate that biogenic magnetic nanoparticles, so-called magnetosomes, represent an attractive alternative for the development of nanoscale particle formulations to enable high and stable conversion rates in biocatalytic flow processes. In addition to their intriguing material characteristics, such as high crystallinity, stable magnetic moments, and narrow particle size distribution, magnetosomes offer the unbeatable advantage over chemically synthesized nanoparticles that foreign protein “cargo” can be immobilized on the enveloping membrane via genetic engineering and thus, stably presented on the particle surface. To exploit these advantages, we develop a modular connector system in which abundant magnetosome membrane anchors are genetically fused with SpyCatcher coupling groups, allowing efficient covalent coupling with complementary SpyTag-functionalized proteins. The versatility of this approach is demonstrated by immobilizing a dimeric phenolic acid decarboxylase to SpyCatcher magnetosomes. The functionalized magnetosomes outperform similarly functionalized commercial particles by exhibiting stable substrate conversion during a 60 h period, with an average space–time yield of 49.2 mmol L–1 h–1. Overall, our results demonstrate that SpyCatcher magnetosomes significantly expand the genetic toolbox for particle surface functionalization and increase their application potential as nano-biocatalysts