Regenerative capacity of reactive astrocytes in vitro and in vivo

Reactive astrogliosis is a reaction of the central nervous system (CNS) common to diverse types of injury, but only upon invasive injury a subset of reactive astrocytes acquires proliferative capacity in vivo and exhibits stem cell potential through self-renewal and multipotency in vitro. Given that in the adult mammalian brain only adult neural stem cells (aNSCs) located in specific niches are able to self-renew and give rise to neurons, it is important to test to which extent reactive astrocytes can enact their NSC potential also in vivo when exposed to different environmental conditions. For this purpose, experimental mouse models were used to investigate (i) whether and to which extent astrocytes in the injured cerebral cortex grey matter exhibit self-renewal in vivo when exposed to sequential pathological stimuli; (ii) whether reactive astrocytes can give rise to different cell types in vivo when placed in neurogenesis-supportive environments. In order to analyze the proliferative behavior of reactive astrocytes in the adult murine cerebral cortex in response to repetitive pathological stimuli, I established a double labeling paradigm based on sequential delivery of two thymidine analogues, BrdU and EdU. Furthermore, in order to verify the results obtained with this paradigm I performed clonal analysis of reactive astrocytes using GlastCreERT2-mediated recombination in the R26-Confetti reporter line. Results from both experimental paradigms demonstrate that a distinct subset of reactive astrocytes within the cortical parenchyma is able to re-enter the cell cycle and give rise to 3-cell clones upon repetitive injuries, which had so far not been observed. Furthermore, astrocyte cell-cycle reentry is modulated by monocyte infiltration, as it was increased in their absence in transgenic CCR2-/- mice. Moreover, we used BrdU and EdU double labeling to investigate whether proliferation was a property confined to a specific subset of astrocytes, or if different sets of reactive astrocytes could be activated to enter cell cycle. Our analysis showed that the astrocyte proliferative pool is not fixed, and new astrocytes can be recruited into proliferation upon a second pathological event. Intriguingly, our results suggest a strong drive towards astroglial population homeostasis, which has so far not been described in these cells. To analyze the differentiation capacity of RAs in vivo, cortical reactive astrocytes and aNSCs from the subependymal zone (SEZ) of adult actin-GFP mice cultured as neurospheres were transplanted heterotypically into the adult dentate gyrus (DG) and the E13 embryonic brain. Our analysis showed that the progeny of reactive astrocytes remained restricted within the glial lineage in both environments, whereas aNSCs gave rise to immature neurons in the DG and to mature neurons in a few regions of the embryonic brain. Taken together although reactive astrocytes show multipotency and can give rise to neurons in vitro, they are largely unable to generate neurons in vivo. Furthermore, in light of a recently reopened debate that questions reactive astrocyte stem cell potential, our results from transplantation experiments provoked further investigation on this matter. There is new evidence supporting that all neurospheres obtained from injured cortical tissue are actually originated from SEZ aNSCs. As our transplantation results showed a distinct differentiation profile of reactive astrocytes when compared to aNSCs in both host environments, we performed experiments to add evidence to this debate. For this purpose, we developed two independent experimental paradigms in which cortical cells (but not SEZ cells) were labeled prior to injury through double transgenic Emx1-GFP mice and through delivery of AAV-iCre into the cortex of floxed GFP-Reporter mice. Our results obtained with both experimental paradigms show that cells of cortical origin can give rise to neurospheres in vitro following stab wound lesion. Altogether, through this study we have achieved many novel insights into astrocyte reaction to injury, regulation of astrocytic population through different proliferation strategies, and into the stem cell potential of reactive astrocytes in vivo. Our findings advance the general understanding of astrocyte biology in the context of CNS pathology and open the way to many new questions in this field

Batch Normalization Preconditioning for Neural Network Training

Batch normalization (BN) is a popular and ubiquitous method in deep learning that has been shown to decrease training time and improve generalization performance of neural networks. Despite its success, BN is not theoretically well understood. It is not suitable for use with very small mini-batch sizes or online learning. In this work, we propose a new method called Batch Normalization Preconditioning (BNP). Instead of applying normalization explicitly through a batch normalization layer as is done in BN, BNP applies normalization by conditioning the parameter gradients directly during training. This is designed to improve the Hessian matrix of the loss function and hence convergence during training. One benefit is that BNP is not constrained on the mini-batch size and works in the online learning setting. We also extend this technique to Bayesian neural networks which are networks that have probability distributions corresponding to the weights and biases instead of single fixed values. In particular, we apply BNP to stochastic gradient Langevin dynamics (SGLD), which is a standard sampling technique for uncertainty estimation in Bayesian neural networks

Kleinhirnvolumen bei Kindern mit Epilepsie

Ziel dieser Studie war die Überprüfung, ob bei Kindern mit Epilepsie Veränderungen des Kleinhirnvolumens mittels MRT detektiert werden können. Es wurden 41 Kinder (3,1 - 18,8 Jahre) mit Epilepsie unbekannter Ursache eingeschlossen (Krankheitsdauer 1,9 ± 3 Jahre). Eine MRT mit 3D-T1w Sequenz wurde zur Volumenanalyse genutzt. Untergruppe A bildeten Kinder mit einem, Untergruppe B mit mehr als einem antiepileptischen Medikament. Zum Vergleich wurden MRT von 26 Kopfschmerzpatienten (5,3 - 17,1 Jahre) analysiert. Die Volumetrie des Kleinhirns erfolgte mittels Region basierter Morphometrie (CAT12). Erhoben wurden Gesamtvolumen, graue und weiße Substanz sowie 48 verschiedene Lobuli (L) des Kleinhirns. Die Kleinhirnvolumina wurden in relativen Anteilen dargestellt. Das Gesamtvolumen des Kleinhirns zeigte keinen signifikanten Unterschied zwischen Fallgruppe (95,22 x 10-3) und Vergleichsgruppe (96,72 x 10 3; p = 0,334). Die weiße Substanz war in der Fallgruppe (23,93 x 10 3, p = 0,039) und Untergruppe A (23,63 x 10-3, p = 0,022) signifikant kleiner als in der Vergleichsgruppe (25,43 x 10 3). Ein signifikant geringeres Volumen wurde in der weißen Substanz von LV links (p = 0,031) und rechts (p = 0,014), LVIIIB links (p = 0,009) und rechts (p = 0,011) sowie LVIIIA links (p = 0,019) nachgewiesen. In Untergruppe A hatte die weiße Substanz des Crus I (p = 0,018) der Fallgruppe ein signifikant kleineres Volumen. Unsere Ergebnisse betonen, dass eine alleinige Betrachtung des Gesamtkleinhirnvolumens nicht ausreicht. Kinder mit Epilepsie weisen in einzelnen Kleinhirnlobuli ein signifikant reduziertes Volumen auf. L V, VI und VIII werden als sensomotorische Areale angesehen. Crus I ist in höhere kognitive Aufgaben involviert (Sprache, Arbeitsgedächtnis, räumliches Vorstellungsvermögen). Die Studie konnte erstmals einen Zusammenhang zwischen Epilepsie im Kindesalter und einem reduzierten Volumen in Anteilen des Kleinhirns zeigen, die wichtig für die Sensomotorik und Kognition sind

O processo de paz entre o governo de Juan Manuel Santos e as Farc: uma análise à luz da escola de Copenhague

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Sócio-Econômico. Relações Internacionais.O objetivo deste trabalho consiste em analisar, a partir dos conceitos fornecidos pela Escola de Copenhague, como se desenvolveu o processo de paz entre o governo colombiano e as FARC que teve seu início em 2011, durante o primeiro mandato de Juan Manuel Santos. Além disso, almeja-se entender quais são as possíveis consequências desse processo, analisado aqui até a realização do plebiscito de 2016, para a securitização das FARC na Colômbia. A complexidade do conflito, que já dura mais de cinquenta anos, é formada por uma série de atores estatais e não estatais que fazem da população civil refém e desafiam os presidentes do país a encontrarem uma solução. Nesse cenário, o grupo guerrilheiro mais antigo do continente americano, as FARC, tem tido uma atuação relevante, devido não só às estratégias de guerrilha, mas também ao uso de diversas atividades ilícitas para manter sua atuação. Esse emprego de inúmeras atividades criminais levou à sua classificação como grupo terrorista e sua inserção na agenda de Segurança Internacional da Colômbia. Para o combate à guerrilha, o governo colombiano buscou tanto conversas pacíficas, quanto políticas de segurança de linha dura, justificadas a partir da securitização da temática. O presente trabalho propõe-se, portanto, a questionar a manutenção da securitização da guerrilha na Colômbia a partir da realização do processo de paz que teve início em 201

Regenerative capacity of reactive astrocytes in vitro and in vivo

Reactive astrogliosis is a reaction of the central nervous system (CNS) common to diverse types of injury, but only upon invasive injury a subset of reactive astrocytes acquires proliferative capacity in vivo and exhibits stem cell potential through self-renewal and multipotency in vitro. Given that in the adult mammalian brain only adult neural stem cells (aNSCs) located in specific niches are able to self-renew and give rise to neurons, it is important to test to which extent reactive astrocytes can enact their NSC potential also in vivo when exposed to different environmental conditions. For this purpose, experimental mouse models were used to investigate (i) whether and to which extent astrocytes in the injured cerebral cortex grey matter exhibit self-renewal in vivo when exposed to sequential pathological stimuli; (ii) whether reactive astrocytes can give rise to different cell types in vivo when placed in neurogenesis-supportive environments. In order to analyze the proliferative behavior of reactive astrocytes in the adult murine cerebral cortex in response to repetitive pathological stimuli, I established a double labeling paradigm based on sequential delivery of two thymidine analogues, BrdU and EdU. Furthermore, in order to verify the results obtained with this paradigm I performed clonal analysis of reactive astrocytes using GlastCreERT2-mediated recombination in the R26-Confetti reporter line. Results from both experimental paradigms demonstrate that a distinct subset of reactive astrocytes within the cortical parenchyma is able to re-enter the cell cycle and give rise to 3-cell clones upon repetitive injuries, which had so far not been observed. Furthermore, astrocyte cell-cycle reentry is modulated by monocyte infiltration, as it was increased in their absence in transgenic CCR2-/- mice. Moreover, we used BrdU and EdU double labeling to investigate whether proliferation was a property confined to a specific subset of astrocytes, or if different sets of reactive astrocytes could be activated to enter cell cycle. Our analysis showed that the astrocyte proliferative pool is not fixed, and new astrocytes can be recruited into proliferation upon a second pathological event. Intriguingly, our results suggest a strong drive towards astroglial population homeostasis, which has so far not been described in these cells. To analyze the differentiation capacity of RAs in vivo, cortical reactive astrocytes and aNSCs from the subependymal zone (SEZ) of adult actin-GFP mice cultured as neurospheres were transplanted heterotypically into the adult dentate gyrus (DG) and the E13 embryonic brain. Our analysis showed that the progeny of reactive astrocytes remained restricted within the glial lineage in both environments, whereas aNSCs gave rise to immature neurons in the DG and to mature neurons in a few regions of the embryonic brain. Taken together although reactive astrocytes show multipotency and can give rise to neurons in vitro, they are largely unable to generate neurons in vivo. Furthermore, in light of a recently reopened debate that questions reactive astrocyte stem cell potential, our results from transplantation experiments provoked further investigation on this matter. There is new evidence supporting that all neurospheres obtained from injured cortical tissue are actually originated from SEZ aNSCs. As our transplantation results showed a distinct differentiation profile of reactive astrocytes when compared to aNSCs in both host environments, we performed experiments to add evidence to this debate. For this purpose, we developed two independent experimental paradigms in which cortical cells (but not SEZ cells) were labeled prior to injury through double transgenic Emx1-GFP mice and through delivery of AAV-iCre into the cortex of floxed GFP-Reporter mice. Our results obtained with both experimental paradigms show that cells of cortical origin can give rise to neurospheres in vitro following stab wound lesion. Altogether, through this study we have achieved many novel insights into astrocyte reaction to injury, regulation of astrocytic population through different proliferation strategies, and into the stem cell potential of reactive astrocytes in vivo. Our findings advance the general understanding of astrocyte biology in the context of CNS pathology and open the way to many new questions in this field

Repetitive injury and absence of monocytes promote astrocyte self-renewal and neurological recovery

Unlike microglia and NG2 glia, astrocytes are incapable of migrating to sites of injury in the posttraumatic cerebral cortex, instead relying on proliferation to replenish their numbers and distribution in the affected region. However, neither the spectrum of their proliferative repertoire nor their postinjury distribution has been examined in vivo. Using a combination of different thymidine analogs and clonal analysis in a model of repetitive traumatic brain injury, we show for the first time that astrocytes that are quiescent following an initial injury can be coerced to proliferate after a repeated insult in the cerebral cortex grey matter. Interestingly, this process is promoted by invasion of monocytes to the injury site, as their genetic ablation (using CCR2(-/-)mice) increased the number of repetitively dividing astrocytes at the expense of newly proliferating astrocytes in repeatedly injured parenchyma. These differences profoundly affected both the distribution of astrocytes and recovery period for posttraumatic behavior deficits suggesting key roles of astrocyte self-renewal in brain repair after injury

What are the Role and Capabilities of Fab Labs as a Contribution to a Resilient City? Insights from the Fab City Hamburg

Recent events such as the COVID-19 pandemic or the Ever-Given accident in the Suez Canal, which have led to local product shortages and negative social and environmental impacts, highlight the need to build resilience in areas that are highly affected by such events: in cities. One aspect of a multidisciplinary concept of resilient cities is the local manufacturing of physical products, which currently is mainly based on globally complex supply chains. The resilience of a city can be impaired if the supply of consumer goods can no longer be guaranteed, e.g., due to the fragility of supply chains. From this perspective, one of several pathways to a more resilient city is the emerging movement of open production sites (so called Fab Labs), where physical products can be produced or repaired in a distributed way by the consumers themselves. In metropolitan areas such as Hamburg, Fab Labs form networks including makerspaces, open workshops and educational institutions – so called Fab Cities. This article highlights the role of Fab Labs with regards to urban resilience and displays the capability of the Fab City Hamburg to contribute to the resilience of the city. To explore these capabilities, semi-structured interviews were conducted with makers and operators, and different Fab Labs were explored via participant observation. This article demonstrates that Fab Labs can contribute to a resilient city - especially from the perspective of manufacturing capability but also regarding the development of technical education. However, there are clear limitations with regards to the vertical range and manufacturing diversity

Microvesicles secreted from equine amniotic cells and their potential role in in vitro cell tendon repair

The regenerative mechanisms ascribed to mesenchymal stem cells (MSCs) are classified into 3 categories: differentiating into damaged cell types, supplying nutrients, and improving survival/functions of the endogenous cells via paracrine actions. However, because of the inhospitable microenvironment of the injured tissues, a proportion of the implanted MSCs may quickly die, suggesting that other mechanisms might be present. This notion is supported by the overlapping beneficial effect (in terms of time of healing) resulted  after the injection of AMCs or of amniotic mesenchymal cells - conditioned medium (AMC-CM)  in equine spontaneous injured tendons and ligaments. Microvesicles (MVs) released by cells are an integral component of the cell-to-cell communication network involved in tissue regeneration.In the present study, MVs secreted by AMCs were investigated with Nanosigth instrument and TEM. Then, the in vitro incorporation of MVs into equine tendon cells was studied by a dose-response curve. Lastly, the ability of MVs to counteract an in vitro inflammatory process induced by lipolysaccaride on tendon cells was studied evaluating the expression of pro-inflammatory genes like metallopeptidase (MPP) 1 and 13, and prostaglandin-endoperoxide synthase 2 (COX2). Results demonstrated that AMCs secreted MVs ranging in size from 100 to 1000 nm with a prevalence of 100-200 nm large MVs. Tendon cells were able to uptake them with an inverse relationship between concentration and time. The greatest incorporation was detectable at 40x106 MVs/ml after 72h. MVs induced down-regulation of MMP1 and MMP13, suggesting that they may have contributed, along with soluble factors, to in vivo tendon regeneration

Digitalisierung der Landwirtschaft

DIGITALISIERUNG DER LANDWIRTSCHAFT Digitalisierung der Landwirtschaft / Kliem, Lea (Rights reserved) ( -

Revealing the last 13,500 years of environmental history from the multiproxy record of a mountain lake (Lago Enol, northern Iberian Peninsula)

This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10933-009-9387-7.We present the Holocene sequence from Lago Enol (43°16′N, 4°59′W, 1,070 m a.s.l.), Cantabrian Mountains, northern Spain. A multiproxy analysis provided comprehensive information about regional humidity and temperature changes. The analysis included sedimentological descriptions, physical properties, organic carbon and carbonate content, mineralogy and geochemical composition together with biological proxies including diatom and ostracod assemblages. A detailed pollen study enabled reconstruction of variations in vegetation cover, which were interpreted in the context of climate changes and human impact. Four distinct stages were recognized for the last 13,500 years: (1) a cold and dry episode that includes the Younger Dryas event (13,500–11,600 cal. year BP); (2) a humid and warmer period characterizing the onset of the Holocene (11,600–8,700 cal. year BP); (3) a tendency toward a drier climate during the middle Holocene (8,700–4,650 cal. year BP); and (4) a return to humid conditions following landscape modification by human activity (pastoral activities, deforestation) in the late Holocene (4,650–2,200 cal. year BP). Superimposed on relatively stable landscape conditions (e.g. maintenance of well established forests), the typical environmental variability of the southern European region is observed at this site.The Spanish Inter-Ministry Commission of Science and Technology (CICYT), the Spanish National Parks agency, the European Commission, the Spanish Ministry of Science, and the European Social Fund