Stochastic model specification search for Gaussian and partial non-Gaussian state space models

Model specification for state space models is a difficult task as one has to decide which components to include in the model and to specify whether these components are fixed or time-varying. To this aim a new model space MCMC method is developed in this paper. It is based on extending the Bayesian variable selection approach which is usually applied to variable selection in regression models to state space models. For non-Gaussian state space models stochastic model search MCMC makes use of auxiliary mixture sampling. We focus on structural time series models including seasonal components, trend or intervention. The method is applied to various well-known time series

Preclinical testing of nanoparticle based drug delivery systems on basis of human serum albumin for targeted drug delivery

Nanopartikuläre Arzneistoffsysteme sind ein viel versprechender Ansatz die speziellen Anforderungen, die an eine Arzneiform gestellt werden, zu erfüllen. Mit ihnen scheint das lang verfolgte Ziel der Pharmaforschung, das gezielte Transportieren ("Drug-Targeting") und das kontrollierte Freisetzen des Arzneistoffs am Wirkort ("Controlled Release") und damit das Minimieren unerwünschter Nebenwirkungen, in greifbare Nähe zu rücken. In der vorliegenden Arbeit konnte durch verschiedene Versuchsansätze in der präklinischen Testung der gezielte Wirkstofftransport zielgerichtet-modifizierter Nanopartikel (NP) auf humanem Serumalbumin (HSA)-Basis sowohl für das spezifische Tumor-Targeting als auch für die Überwindung der Blut-Hirn-Schranke (BHS) gezeigt werden. Die NP für das spezifische Tumor-Targeting waren mit dem Zytostatikum Doxorubicin beladen und mit dem tumorspezifischen Liganden Trastuzumab für ein Mammakarzinom-Zellen-Targeting oder DI17E6 für ein Melanom-Zellen-Targeting modifiziert. Ihre zielgerichtete Funktionalität konnte an verschiedenen Target-exprimierenden-Zelllinien gezeigt werden. Dabei konnte ihre spezifische zelluläre Bindung, Aufnahme und subzellulären Verteilung verifiziert werden. Die Ligand-modifizierten NP wurden bei diesen Untersuchungen spezifisch in die Zielzellen aufgenommen, während die unmodifizierten Kontroll-Partikel unspezifisch an der Zellmembran klebten. Die Freisetzung des Doxorubicins in einer biologisch aktiven Form konnte anhand entsprechender Zellviabilitäts-Assays gezeigt werden. Des Weiteren konnte gezeigt werden, dass der nanopartikulär transportierte Wirkstoff über den Rezeptor-internalisierenden Aufnahmeweg nicht in den Endosomen oder Lysosomen akkumulierte und damit inaktiv war, sondern dass er in wirksamer Form freigesetzt wurde. Als Besonderheit wurde mit DI17E6 für das spezifische Melanom-Zellen-Targeting ein Antikörper als ziel-orientierter Ligand eingesetzt, der zusätzliche anti-tumorale Eigenschaften hat, die bei der Ankopplung an die NP-Oberfläche erhalten werden sollten. Durch speziell entwickelte in vitro Assays, die auf diese Eigenschaften abzielten, konnte der Erhalt der biologischen Wirksamkeit des Antikörpers bestätigt werden. Mit derartigen nanopartikulären Formulierungen, basierend auf biologisch abbau¬barem HSA, modifiziert mit entsprechenden zielgerichteten Liganden und anti-tumoralen Wirkstoffen, sollte aufgrund der hier gezeigten präklinischen Daten eine spezifische Tumortherapie möglich sein. Zum Überwinden der BHS wurden NP getestet, die mit Apolipoprotein E (ApoE) modifiziert waren. Dabei handelte es sich zum einen um leere NP für Aufnahmemechanismus-Studien und zum anderen um Obidoxim-beladene NP für Transportstudien. Bei Obidoxim handelt es sich um einen Vertreter der Stoffklasse der Oxime. Diese werden als Antidote bei Organophosphat (OP)-Vergiftungen eingesetzt. Oxime können die nach einer OP-Vergiftung inhibierte lebensnotwendige Acetylcholinesterase (AChE) reaktivieren. Da Oxime die BHS aber kaum überwinden können, wird die in den zentralnervösen Kompartimenten inhibierte AChE nicht in therapeutisch ausreichendem Maß erreicht. Daher sollte beispielhaft Obidoxim nanopartikulär-vermittelt über die BHS transportiert werden. Für beide Formulierungen konnte die spezifische zelluläre Bindung, Aufnahme und die subzelluläre Verteilung sowie ihre für ein BHS-Targeting kompatiblen, untoxischen Eigenschaften gezeigt werden. Mit den ApoE-modifizierten unbeladenen NP konnte durch verschiedene Koinkubations- und Hemmexperimente eindeutig die Beteiligung der "Low Density Lipoprotein" (LDL)-Rezeptor-Familie, und besonders des "Low Density Lipoprotein Receptor Related Protein" (LRP), bei der spezifischen ApoE-vermittelten NP-Aufnahme gezeigt werden. Dabei ließ sich die NP-Aufnahme auf zwei Wegen hemmen. Zum einen konnte von der zellulären Seite aus der beteiligte Aufnahme-Rezeptors mit dem "Receptor Associated Protein" gehemmt werden, wodurch eine spezifische ApoE-vermittelte NP-Aufnahme über eine Rezeptor-Bindung verhindert wurde. Zum anderen konnte aber auch, durch Blockade des ApoE auf der Partikeloberfläche mittels löslicher Fragmente des LRP, die ApoE-vermittelte NP-Aufnahme von nanopartikulärer Seite gehemmt werden. Durch die Kenntnis des Aufnahmemechanismus der nanopartikulären Formulierungen sollte es für zukünftige Entwicklungen im breiten Feld der BHS-Forschung möglich sein, sehr spezifische und effektivere Carrier maßzuschneidern. Zu Untersuchungen des Wirkstofftransports wurden frisch isolierte porcine Gehirnkapillarendothel-Zellen im Transwell-System als adäquates in vitro BHS-Modell etabliert und eingesetzt. Für den Nachweis des tatsächlichen Obidoxim-Transports wurde ein biologischer Assay entwickelt, der gemäß der therapeutischen Funktion von Oximen nach OP-Vergiftungen auf die Reaktivierung OP-vergifteter AChE abzielte. Es konnte gezeigt werden, dass nanopartikuläre Formulierungen tatsächlich einen verbesserten Transport von Obidoximen gegenüber freiem Obidoxim in einem in vitro BHS-Modell vermitteln. Diese nanopartikulären Transportsysteme stellen daher ein bisher einzigartiges, viel versprechendes Hilfsmittel zum Transport von Oximen über die BHS dar. Durch die in dieser Arbeit dargestellten Untersuchungen konnte insgesamt gezeigt werden, dass NP auf HSA-Basis für einen zielgerichteten Wirkstofftransport geeignet sind und aufgrund ihrer biokompatiblen, bioabbaubaren Eigenschaften einen viel versprechenden Ansatz für die zukünftige Pharmaforschung darstellen.Nanoparticulate drug delivery systems are a promising approach to achieve the special requirements to a drug delivery system. With them the long pursued goal of the pharmaceutical research, the specific "drug targeting" and the "controlled release" of the drug thus minimizing unwanted side effects seems to get into reach. In the present study the specific drug transport by target-oriented modified nanoparticles (NP) based on human serum albumin (HSA) could be shown by different experiments in the field of preclinical testing both for the specific tumor targeting and for the overcoming of the blood-brain barrier (BBB). The NP for the specific tumor targeting were loaded with the cytostatic drug Doxorubicin and were modified with the tumor-specific ligand Trastuzumab for a breast cancer cell targeting or DI17E6 for a melanoma cell targeting. Their target-oriented functionality could be shown by the use of different target-expressing cell lines. Thereby, their specific cellular binding, uptake and subcellular distribution could be verified. The ligand-modified NP were specifically taken up by the target-expressing cell lines, whereas the unmodified control particles stuck unspecifically on the outer cell membrane. The release of the Doxorubicin in a biologically active form could be shown by adequate cell viability assays. Furthermore, it could be shown that the nanoparticulate transported cytostatic drug over the receptor-internalizing pathway did not accumulate in the Endosomes or Lysosomes and was therefore inactive, but it was released in active form. As a special feature concerning the specific melanoma targeting the antibody DI17E6 was used as a target-oriented ligand, which has additional anti-tumoral characteristics, which should be preserved by the coupling onto the NP surface. The preservation of the biological effectiveness of the antibody could be confirmed by individually developed in vitro assays concerning these special features. Due to the preclinical data shown here, a specific tumor therapy should be possible with such nanoparticulate formulations based on biodegradable HSA, modified with target-oriented ligands and cytostatic drugs. For the overcoming of the BBB NP were tested, which have been modified with Apolipoprotein E (ApoE). Thereby, it concerned empty NP for uptake mechanism studies and Obidoxime loaded NP for transport studies. Obidoxime is a representative of the substance class of the Oximes. They are used as antidotes after organophosphate (OP) poisonings. Oximes can re-activate the essential acetylcholinesterase (AChE) inhibited after an OP poisoning. But Oximes can hardly cross the BBB and therefore do not reach the inhibited AChE in the central nervous system in therapeutically sufficient manner. Therefore, exemplary Obidoxime should be transported individually over the BBB mediated by nanoparticulate drug delivery systems. For both formulations the specific cellular binding, uptake and the subcellular distribution could be shown as well as their non toxic characteristics compatible for a BBB targeting. With the ApoE modified empty NP the participation of the "Low Density Lipoprotein" (LDL)-receptor family, and particularly the "Low Density Lipoprotein Receptor Related protein" (LRP) by the specific ApoE mediated NP uptake could clearly be shown by different co-incubations and inhibition experiments. The NP uptake itself could be inhibited in two ways. On the one hand on the cellular side the involved uptake receptor could be inhibited with the "Receptor Associated protein". Thus a specific ApoE mediated NP uptake by receptor binding was prevented. On the other hand the ApoE mediated NP uptake could be impeded on the nanoparticulate side by blockage of the ApoE on the particle surface by means of soluble fragments of the LRP. Through the knowledge of the transport mechanism of the nanoparticulate formulations it should be possible to tailor very specific and more effective carriers for future developments in the broad field of the BBB research. As an adequate in vitro BBB model for drug transport studies freshly isolated porcine brain capillary endothelial cells were established and used within the Transwell system. For proof of the effective Obidoxime transport a biological assay was developed, which according to the therapeutic function of oximes after OP poisonings aimed at the reactivation of OP inhibited AChE. It could be shown that nanoparticulate formulations really improved the transport of Obidoximes over an in vitro BBB model in comparison to the free Obidoxime. Therefore, these nanoparticulate transport systems represent a unique and promising tool for the transport of Oximes over the BBB. Altogether, it could be shown by the research represented in this work that NP based on HSA are suitable for a specific drug transport and due to their biocompatible, biodegradable nature they are a promising approach in future pharmaceutical research

Si nous les évaluons, apprendront-ils? Le point de vue des étudiants sur la complexité de l’évaluation pour l’apprentissage

Introduction: Assessment can positively influence learning, however designing effective assessment-for-learning interventions has proved challenging. We implemented a mandatory assessment-for-learning system comprising a workplace-based assessment of non-medical expert competencies and a progress test in undergraduate medical education and evaluated its impact. Methods: We conducted semi-structured interviews with year-3 and 4 medical students at McGill University to explore how the assessment system had influenced their learning in year 3. We conducted theory-informed thematic analysis of the data. Results: Eleven students participated, revealing that the assessment influenced learning through several mechanisms. Some required little student engagement (i.e., feed-up, test-enhanced learning, looking things up after an exam). Others required substantial engagement (e.g., studying for tests, selecting raters for quality feedback, using feedback). Student engagement was moderated by the perceived credibility of the system and of the costs and benefits of engagement. Credibility was shaped by students’ goals-in-context: becoming a good doctor, contributing to the healthcare team, succeeding in assessments. Discussion: Our assessment system failed to engage students enough to leverage its full potential. We discuss the inherent flaws and external factors that hindered student engagement. Assessment designers should leverage easy-to-control mechanisms to support assessment-for-learning and anticipate significant collaborative work to modify learning cultures.Introduction : L’évaluation peut influencer positivement l’apprentissage mais la conception de dispositifs d’évaluation pour l’apprentissage efficaces s’avère difficile. Nous avons implanté en formation prédoctorale un système obligatoire d’évaluation pour l’apprentissage comprenant une évaluation en milieu clinique des compétences transversales et un test de rendement progressif, puis évalué ses effets. Méthodes : Nous avons mené des entretiens semi-dirigés avec des étudiants en troisième et quatrième années de médecine à l’Université McGill pour explorer la manière dont le système d’évaluation avait influencé leur apprentissage au cours de la troisième année. Nous avons effectué une analyse thématique, informée par la théorie, des données. Résultats : Onze étudiants ont participé. Les résultats indiquent que l’évaluation a influencé leur apprentissage par le biais de plusieurs mécanismes différents. Certains d’entre eux nécessitaient une implication faible de la part de l’étudiant, comme l’identification des objectifs à atteindre (feed-up), l’apprentissage amélioré par les tests, la recherche d’informations après un examen. D’autres exigeaient une implication importante (par exemple, étudier pour les tests, sélectionner les évaluateurs pour obtenir une rétroaction de qualité, mettre à profit la rétroaction). L’implication des étudiants était modulée par leur perception des avantages et des inconvénients de s’impliquer, et de la crédibilité du système. Cette dernière était influencée par les objectifs-en-contexte des étudiants: devenir un bon médecin, contribuer à l’équipe soignante, réussir les épreuves d’évaluation. Discussion : Notre système d’évaluation n’a pas réussi à impliquer suffisamment les étudiants que pour réaliser son potentiel. Nous abordons les défauts inhérents au système ainsi que les facteurs externes qui ont entravé l’implication des apprenants. Pour implanter efficacement un dispositif d’évaluation pour l’apprentissage, les concepteurs d’évaluations devraient optimiser les mécanismes qui sont faciles à contrôler et être prêts à s’investir dans un important travail de collaboration pour changer les cultures d’apprentissage

Development of Myeloid Dendritic Cells under the Influence of Sexual Hormones Visualized using Scanning and Transmission Electron Microscopy

Dendritic cells (DCs) are antigen-presenting cells, which are mediated by MHC-class II molecules reacting with T-helper cells, eliciting a broad spectrum of immune reactions at cellular and humoral levels depending on their subtypes. DCs are also able to cross-present peptides from intracellular proteins as well as from intracellular pathogens via MHC-class I molecules by inducing MHC-class I–restricted cytotoxic T cells, which are also able to destroy cells undergoing malignant transformation. DCs originate from CD34+ hematopoietic stem cells but can also develop from monocytes. The local or systemic milieu of cytokines and steroid hormones significantly influences the generation of particular DC subtypes such as the classical myeloid DCs such as cDC1 and cDC2 as well as the plasmacytoid DCs. These subtypes are able to induce specific Th1- and Th17-dependent, Th2-dependent, or regulatory immune responses, respectively. Immature DCs take up extracellular pathogens that are presented by MHC molecules that are upregulated during maturation. Immature and mature DCs can be characterized by morphological and biochemical features that are outlined in this article. In addition, DCs are under control of sexual hormones. Estrogen receptor ligands are potent modulators of hemopoiesis and immune function in health and disease, influencing key cytokines promoting the maturation of DCs. DC differentiation is mainly regulated by binding of estradiol to ERα. Estrogen promotes the differentiation of immature DC subsets derived from bone marrow precursors or from myeloid progenitors. In contrast to estrogen, progesterone inhibits DC maturation, causing a decreased immunity in pregnancy or in postmenopausal women, where elevated levels of progesterone result in the production of Th2 cytokines. The influence of estrogen and progesterone on DC maturation has been demonstrated in own in vitro experiments using fluorescence microscopy and cell sorting and, above all, by visualization using SEM and TEM. At the end of this article, pits and falls concerning the treatment of malignancies with living DC vaccines are discussed

Vitamin D: beyond bone.

In recent years, vitamin D has been received increased attention due to the resurgence of vitamin D deficiency and rickets in developed countries and the identification of extraskeletal effects of vitamin D, suggesting unexpected benefits of vitamin D in health and disease, beyond bone health. The possibility of extraskeletal effects of vitamin D was first noted with the discovery of the vitamin D receptor (VDR) in tissues and cells that are not involved in maintaining mineral homeostasis and bone health, including skin, placenta, pancreas, breast, prostate and colon cancer cells, and activated T cells. However, the biological significance of the expression of the VDR in different tissues is not fully understood, and the role of vitamin D in extraskeletal health has been a matter of debate. This report summarizes recent research on the roles for vitamin D in cancer, immunity and autoimmune diseases, cardiovascular and respiratory health, pregnancy, obesity, erythropoiesis, diabetes, muscle function, and aging

Welchen Einfluss hat der Weidegang auf das Tierwohl von Milchkühen? Erste Ergebnisse des Welfare Quality® Protokolls bei ganzjähriger Stallhaltung und Sommerweidegang

Grazing provides livestock better opportunities to act out their species specific behaviour compared to the restrictive stable conditions. Studies on the effect of grazing on animal welfare in dairy farming in Germany are rare and have not been conducted under the specific conditions of organic dairy farming. The aim of the present study was to examine the effects of grazing on animal welfare of dairy cows in organic and conventional farming based on the Welfare Quality® protocol for dairy cattle. In this paper, we present the initial evaluation of a comparison between zero grazing and summer grazing. The first results indicate an improvement in most welfare principles during the summer months for dairy cows with summer grazing, except for between winter and summer in zero grazing farms. In conclusion, grazing offers a great potential for improved animal welfare, while the benefitial effects of grazing are not guaranteed in event of suboptimal management

How to track cellular aging of mesenchymal stromal cells?

Mesenchymal stromal cells (MSC) are currently tested in a large number of clinical trials and raise high hope in regenerative medicine. These cells have to be expanded in vitro before transplantation and several studies demonstrated that long-term culture evokes continuous changes in MSC: proliferation rate decays, the cell size increases, differentiation potential is affected, chromosomal instabilities may arise and molecular changes are acquired. Long-term culture of cell preparations might also have therapeutic consequences, although this has hardly been addressed in ongoing trials so far. Reliable therapeutic regimens necessitate quality control of cellular products. This research perspective summarizes available methods to track cellular aging of MSC. We have demonstrated that gene expression changes and epigenetic modifications are continuously acquired during replicative senescence. Molecular analysis of a suitable panel of genes might provide a robust tool to assess efficiency and safety of long-term expansion

Arranjos Cognitivos:: Abrangências e Limitações Representacionais

This study evaluates the quantitative (sensorial field’s dimensions) and qualitative (configuration’s patterns, qualias and spatial/time) characteristics of missing and remaining sensorial modalities and how they affect the cognitive arrangement and the representational fluency of sensorial impaired individuals (blindness and deafness). It is suggested that precocious and massive use of the predominantly configurational nature of the visual sensorial modality, the main modality remaining on born deaf subjects, inhibit their representational production, while the intensive and precocious use of the predominantly insinuating nature of the auditive sensorial modality, the main modality on born blind subjects, encourages representational production on them.Este artigo avalia as características quantitativas (dimensões dos campos sensoriais) e qualitativas (padrões configuracionais, qualias e tempo/espaciais) das modalidades sensoriais faltantes e remanescentes e como elas afetam o arranjo cognitivo e a fluência representacional de indivíduos sensorialmente privados (cegos e surdos). Sugere-se que a utilização precoce e maciça do caráter predominantemente configuracional da modalidade sensorial visual, principal modalidade remanescente nos surdos congênitos, iniba a produção representacional nesses indivíduos, enquanto que o uso intensivo e precoce do caráter predominantemente insinuador da modalidade sensorial auditiva, principal modalidade nos cegos congênitos, incentive a produção representacional nesses últimos