Validierung geeigneter entwicklungsabhängiger Expressionsmarker für ein stammzellassoziiertes sphäroides In-vitro-Kultursystem hochgradiger Gliome

Um weiterführende Therapien für hochgradige Gliome bzw. Glioblastome zu entwickeln, sind geeignete In-vitro-Modelle unumgänglich. Die Kultivierung von stammzellassoziierten Sphärenformationen mit dem Oberflächenprotein CD133 als Stammzellmarker ist dabei eine interessante Möglichkeit, wobei CD133 zuletzt als potentieller Stammzellmarker in Frage gestellt wird. Ziel dieser Arbeit ist es, einzelne Marker oder Expressionsmuster zu charakterisieren, die zuverlässig stammzellassoziierter Sphären-Assays definieren. Dafür wurden aus Frischresektaten nach einem etablierten Stammzellisolationsprotokoll Sphärenkulturen erzeugt und sphäreninduzierten Vergleichskulturen aus vormals adhärenten Primärkulturen, immortalen Zelllinien sowie zusätzlich adhärenten Primärkulturen gegenübergestellt. Dabei setzten sich die Stammzellisolierten auf physiologischer Ebene wie der Sphärenbildungsdauer, mit niedriger metabolischer Aktivität aber verstärkter Migrationstendenz signifikant ab. Eine Immunfluoreszenzanalyse charakterisierte zuverlässig Sphären- und Differenzierungsstadien in allen Gruppen, wobei die Expression von CD133 und Sox2 im Zuge der Differenzierung ab und die der Intermediärfilamente (Nestin, GFAP, Vimentin) zunahmen Das mRNA-Expressionsmuster der stammzellisolierten Sphären hob sich durch eine verstärkte, weitgehend signifikante Expression der Marker MUSASH-1, NESTIN, NOTCH-1 sowie GFAP von den drei Vergleichsgruppen ab. Die Expressionen von CD133, SOX2, NANOG und OCT4 trennte die Gruppen nicht. Die Stammzellisolierten bestätigen stammzellassoziierte Merkmale gegenüber den Vergleichsgruppen, welche sich nicht voneinander unterschieden. Diese zeigten ebenfalls die stärkste Expression des potentiellen Stammzellmarkers MUSASHI-1 auf mRNA-Ebene, der demnach als geeigneter Referenzmarker für weiterführende Analysen betrachtet werden kann. Zusätzlich geht die verstärkten NESTIN- und NOTCH-1-Expression auf mRNA-Ebene mit diesen stammzellassoziierten Sphärenkulturen einher

Bayesian calibration and sensitivity analysis of heat transfer models for fire insulation panels

International audienc

On the importance of low-frequency signals in functional and molecular photoacoustic computed tomography

In photoacoustic computed tomography (PACT) with short-pulsed laser excitation, wideband acoustic signals are generated in biological tissues with frequencies related to the effective shapes and sizes of the optically absorbing targets. Low-frequency photoacoustic signal components correspond to slowly varying spatial features and are often omitted during imaging due to the limited detection bandwidth of the ultrasound transducer, or during image reconstruction as undesired background that degrades image contrast. Here we demonstrate that low-frequency photoacoustic signals, in fact, contain functional and molecular information, and can be used to enhance structural visibility, improve quantitative accuracy, and reduce spare-sampling artifacts. We provide an in-depth theoretical analysis of low-frequency signals in PACT, and experimentally evaluate their impact on several representative PACT applications, such as mapping temperature in photothermal treatment, measuring blood oxygenation in a hypoxia challenge, and detecting photoswitchable molecular probes in deep organs. Our results strongly suggest that low-frequency signals are important for functional and molecular PACT

Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS

We report the discovery of 74 new pulsating DA white dwarf stars, or ZZ Cetis, from the data obtained by the Transiting Exoplanet Survey Satellite mission, from Sectors 1 to 39, corresponding to the first 3 cycles. This includes objects from the Southern hemisphere (Sectors 1–13 and 27–39) and the Northern hemisphere (Sectors 14–26), observed with 120 s- and 20 s-cadence. Our sample likely includes 13 low-mass and one extremely low-mass white dwarf candidate, considering the mass determinations from fitting Gaia magnitudes and parallax. In addition, we present follow-up time series photometry from ground-based telescopes for 11 objects, which allowed us to detect a larger number of periods. For each object, we analysed the period spectra and performed an asteroseismological analysis, and we estimate the structure parameters of the sample, i.e. stellar mass, effective temperature, and hydrogen envelope mass. We estimate a mean asteroseismological mass of 〈Msis〉 = 0.635 ± 0.015 M⊙, excluding the candidate low or extremely low-mass objects. This value is in agreement with the mean mass using estimates from Gaia data, which is 〈Mphot〉 = 0.631 ± 0.040 M⊙, and with the mean mass of previously known ZZ Cetis of 〈M*〉 = 0.644 ± 0.034 M⊙. Our sample of 74 new bright ZZ Cetis increases the number of known ZZ Cetis by ∼20 per cent

Prominent role of volcanism in Common Era climate variability and human history

Climate reconstructions for the Common Era are compromised by the paucity of annually-resolved and absolutely-dated proxy records prior to medieval times. Where reconstructions are based on combinations of different climate archive types (of varying spatiotemporal resolution, dating uncertainty, record length and predictive skill), it is challenging to estimate past amplitude ranges, disentangle the relative roles of natural and anthropogenic forcing, or probe deeper interrelationships between climate variability and human history. Here, we compile and analyse updated versions of all the existing summer temperature sensitive tree-ring width chronologies from the Northern Hemisphere that span the entire Common Era. We apply a novel ensemble approach to reconstruct extra-tropical summer temperatures from 1 to 2010 CE, and calculate uncertainties at continental to hemispheric scales. Peak warming in the 280s, 990s and 1020s, when volcanic forcing was low, was comparable to modern conditions until 2010 CE. The lowest June–August temperature anomaly in 536 not only marks the beginning of the coldest decade, but also defines the onset of the Late Antique Little Ice Age (LALIA). While prolonged warmth during Roman and medieval times roughly coincides with the tendency towards societal prosperity across much of the North Atlantic/European sector and East Asia, major episodes of volcanically-forced summer cooling often presaged widespread famines, plague outbreaks and political upheavals. Our study reveals a larger amplitude of spatially synchronized summer temperature variation during the first millennium of the Common Era than previously recognised

Identification and characterization of CKLiK, a novel granulocyteCa^(++)/calmodulin-dependent kinase

Human granulocytes are characterized by a variety of specific effector functions involved in host defense. Several widely expressed protein kinases have been implicated in the regulation of these effector functions. A polymerase chain reaction- based strategy was used to identify novel granulocyte-specific kinases.Anovel protein kinase complementary DNA with an open reading frame of 357 amino acids was identified with homology to calciumcalmodulin- dependent kinase I (CaMKI). This has been termed CaMKI-like kinase (CKLiK). Analysis of CKLiK messenger RNA (mRNA) expression in hematopoietic cells demonstrated an almost exclusive expression in human polymorphonuclear leukocytes (PMN). Up-regulation of CKLiK mRNA occurs during neutrophilic differentiation of CD341 stem cells. CKLiK kinase activity was dependent on Ca11 and calmodulin as analyzed by in vitro phosphorylation of cyclic adenosine monophosphate responsive element modulator (CREM). Furthermore, CKLiKtransfected cells treated with ionomycin demonstrated an induction of CREbinding protein (CREB) transcriptional activity compared to control cells. Additionally, CaMK-kinasea enhanced CKLiK activity. In vivo activation of CKLiK was shown by addition of interleukin (IL)-8 to a myeloid cell line stably expressing CKLiK. Furthermore inducible activation of CKLiK was sufficient to induce extracellular signal-related kinase (ERK) mitogen-activated protein (MAP) kinase activity. These data identify a novel Ca11/calmodulin-dependent PMNspecific kinase that may play a role in Ca11-mediated regulation of human granulocyte functions

Microenvironmental Influence on Pre-Clinical Activity of Polo-Like Kinase Inhibition in Multiple Myeloma: Implications for Clinical Translation

Polo-like kinases (PLKs) play an important role in cell cycle progression, checkpoint control and mitosis. The high mitotic index and chromosomal instability of advanced cancers suggest that PLK inhibitors may be an attractive therapeutic option for presently incurable advanced neoplasias with systemic involvement, such as multiple myeloma (MM). We studied the PLK 1, 2, 3 inhibitor BI 2536 and observed potent (IC50<40 nM) and rapid (commitment to cell death <24 hrs) in vitro activity against MM cells in isolation, as well as in vivo activity against a traditional subcutaneous xenograft mouse model. Tumor cells in MM patients, however, don't exist in isolation, but reside in and interact with the bone microenvironment. Therefore conventional in vitro and in vivo preclinical assays don't take into account how interactions between MM cells and the bone microenvironment can potentially confer drug resistance. To probe this question, we performed tumor cell compartment-specific bioluminescence imaging assays to compare the preclinical anti-MM activity of BI 2536 in vitro in the presence vs. absence of stromal cells or osteoclasts. We observed that the presence of these bone marrow non-malignant cells led to decreased anti-MM activity of BI 2536. We further validated these results in an orthotopic in vivo mouse model of diffuse MM bone lesions where tumor cells interact with non-malignant cells of the bone microenvironment. We again observed that BI 2536 had decreased activity in this in vivo model of tumor-bone microenvironment interactions highlighting that, despite BI 2536's promising activity in conventional assays, its lack of activity in microenvironmental models raises concerns for its clinical development for MM. More broadly, preclinical drug testing in the absence of relevant tumor microenvironment interactions may overestimate potential clinical activity, thus explaining at least in part the gap between preclinical vs. clinical efficacy in MM and other cancers