scholarly journals Hepatic stellate cells: current state and open questions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Claus Kordes ◽  
Hans H. Bock ◽  
Doreen Reichert ◽  
Petra May ◽  
Dieter Häussinger
Keyword(s):  
Hepatic Stellate Cells ◽  
Stellate Cells ◽  
Essential Elements ◽  
Future Research ◽  
Heinrich Heine ◽  
Current State ◽  
Open Questions ◽  
Sinusoidal Endothelium ◽  
Cell Niche ◽  
Space Of Disse

Abstract This review article summarizes 20 years of our research on hepatic stellate cells within the framework of two collaborative research centers CRC575 and CRC974 at the Heinrich Heine University. Over this period, stellate cells were identified for the first time as mesenchymal stem cells of the liver, and important functions of these cells in the context of liver regeneration were discovered. Furthermore, it was determined that the space of Disse – bounded by the sinusoidal endothelium and hepatocytes – functions as a stem cell niche for stellate cells. Essential elements of this niche that control the maintenance of hepatic stellate cells have been identified alongside their impairment with age. This article aims to highlight previous studies on stellate cells and critically examine and identify open questions and future research directions.

Second language structural priming: A critical review and directions for future research

2017 ◽  
Vol 34 (4) ◽  
pp. 539-552 ◽  
Author(s):  
Carrie N. Jackson
Keyword(s):  
Second Language ◽  
Future Research ◽  
Structural Priming ◽  
Cognitive Mechanisms ◽  
L2 Acquisition ◽  
Current State ◽  
Current Review ◽  
Open Questions ◽  
Key Issues ◽  
State Of Research

The last 15 years has seen a tremendous growth in research on structural priming among second language (L2) speakers. Structural priming is the phenomenon whereby speakers are more likely to repeat a structure they have recently heard or produced. Research on L2 structural priming speaks to key issues regarding the underlying linguistic and cognitive mechanisms that support L2 acquisition and use, and the extent to which lexical and grammatical information are shared across an L2 speaker’s languages. As the number of researchers investigating L2 priming and its implications for L2 learning continues to grow, it is important to assess the current state of research in this area and establish directions for continued inquiry. The goal of the current review is to provide an overview of recent research on within-language L2 structural priming, with an eye towards the open questions that remain.

Meinungsbildung in der Netzöffentlichkeit

2019 ◽  
Keyword(s):  
Social Media ◽  
Public Communication ◽  
Future Research ◽  
Digital Revolution ◽  
The Public ◽  
Empirical Basis ◽  
Current State ◽  
Open Questions ◽  
State Of Research

This volume offers insights into current research on the reception and effects of the digital revolution in public communication in the field of communication science. The contributions it contains deal with questions about the use of news on Facebook, the articulation of opinions on the public Net and the influencing of opinions on social media (e.g. by influencers). They document the current state of research and knowledge in this field, answer current open questions on an empirical basis and provide suggestions for future research. With contributions by Patrick Weber, Frank Mangold, Miriam Steiner, Melanie Magin, Birgit Stark, Pascal Jürgens, Anna Sophie Kümpel, Larissa Leonhard, Veronika Karnowski, Claudia Wilhelm, Ines Engelmann, Stefan Geiß, German Neubaum, Manuel Cargnino, Davina Berthelé, Priska Breves, Helene Schüler, Benedikt Spangardt, Kerstin Thummes

Hepatic and pancreatic stellate cells in focus

2009 ◽  
Vol 390 (10) ◽  
Author(s):  
Claus Kordes ◽  
Iris Sawitza ◽  
Dieter Häussinger
Keyword(s):  
Cell Biology ◽  
Stellate Cell ◽  
Stellate Cells ◽  
Pancreatic Stellate Cells ◽  
Differentiation Potential ◽  
Undifferentiated Cells ◽  
Cell Niche ◽  
Space Of Disse

Abstract Stellate cells are vitamin A-storing cells of liver and pancreas and have been described in all vertebrates ranging from lampreys (primitive fish) to humans, demonstrating their major importance. This cell type is thought to contribute to fibrosis, a condition characterized by an excess deposition of extracellular matrix proteins. Recently, the expression of stem/progenitor cell markers, such as CD133 (prominin-1) and Oct4, was discovered in hepatic stellate cells (HSCs) of rats. Moreover, HSCs possess signaling pathways important for maintenance of stemness and cell differentiation, such as hedgehog, β-catenin-dependent Wnt, and Notch signaling, and are resistant to CD95-mediated apoptosis. In analogy to a stem cell niche, some characteristics of quiescent HSC are maintained by aid of a special microenvironment located in the space of Dissé. Finally, stellate cells display a differentiation potential as investigated in vitro and in vivo. Collectively all these properties are congruently found in stem/progenitor cells and support the concept that stellate cells are undifferentiated cells, which might play an important role in liver regeneration. The present review highlights findings related to this novel aspect of stellate cell biology.

scholarly journals Anaphora With Non-nominal Antecedents in Computational Linguistics: a Survey

2018 ◽  
Vol 44 (3) ◽  
pp. 547-612 ◽  
Author(s):  
Varada Kolhatkar ◽  
Adam Roussel ◽  
Stefanie Dipper ◽  
Heike Zinsmeister
Keyword(s):  
Computational Linguistics ◽  
Question Answering ◽  
Future Research ◽  
Good Picture ◽  
Text Understanding ◽  
Theoretical Approaches ◽  
Current State ◽  
Open Questions ◽  
Work Done ◽  
Computational Systems

This article provides an extensive overview of the literature related to the phenomenon of non-nominal-antecedent anaphora (also known as abstract anaphora or discourse deixis), a type of anaphora in which an anaphor like “that” refers to an antecedent (marked in boldface) that is syntactically non-nominal, such as the first sentence in “It’s way too hot here. That’s why I’m moving to Alaska.” Annotating and automatically resolving these cases of anaphora is interesting in its own right because of the complexities involved in identifying non-nominal antecedents, which typically represent abstract objects such as events, facts, and propositions. There is also practical value in the resolution of non-nominal-antecedent anaphora, as this would help computational systems in machine translation, summarization, and question answering, as well as, conceivably, any other task dependent on some measure of text understanding. Most of the existing approaches to anaphora annotation and resolution focus on nominal-antecedent anaphora, classifying many of the cases where the antecedents are syntactically non-nominal as non-anaphoric. There has been some work done on this topic, but it remains scattered and difficult to collect and assess. With this article, we hope to bring together and synthesize work done in disparate contexts up to now in order to identify fundamental problems and draw conclusions from an overarching perspective. Having a good picture of the current state of the art in this field can help researchers direct their efforts to where they are most necessary. Because of the great variety of theoretical approaches that have been brought to bear on the problem, there is an equally diverse array of terminologies that are used to describe it, so we will provide an overview and discussion of these terminologies. We also describe the linguistic properties of non-nominal-antecedent anaphora, examine previous annotation efforts that have addressed this topic, and present the computational approaches that aim at resolving non-nominal-antecedent anaphora automatically. We close with a review of the remaining open questions in this area and some of our recommendations for future research.

scholarly journals Space of Disse: a stem cell niche in the liver

2019 ◽  
Vol 401 (1) ◽  
pp. 81-95 ◽  
Author(s):  
Dieter Häussinger ◽  
Claus Kordes
Keyword(s):  
Stem Cell ◽  
Stem Cell Niche ◽  
Stellate Cells ◽  
Cell Types ◽  
Trophic Factors ◽  
Perivascular Niche ◽  
Diseased Liver ◽  
Cell Niche ◽  
Space Of Disse ◽  
Parenchymal Cells

Abstract Recent evidence indicates that the plasticity of preexisting hepatocytes and bile duct cells is responsible for the appearance of intermediate progenitor cells capable of restoring liver mass after injury without the need of a stem cell compartment. However, mesenchymal stem cells (MSCs) exist in all organs and are associated with blood vessels which represent their perivascular stem cell niche. MSCs are multipotent and can differentiate into several cell types and are known to support regenerative processes by the release of immunomodulatory and trophic factors. In the liver, the space of Disse constitutes a stem cell niche that harbors stellate cells as liver resident MSCs. This perivascular niche is created by extracellular matrix proteins, sinusoidal endothelial cells, liver parenchymal cells and sympathetic nerve endings and establishes a microenvironment that is suitable to maintain stellate cells and to control their fate. The stem cell niche integrity is important for the behavior of stellate cells in the normal, regenerative, aged and diseased liver. The niche character of the space of Disse may further explain why the liver can become an organ of extra-medullar hematopoiesis and why this organ is frequently prone to tumor metastasis.

scholarly journals Mechanical homeostasis in tissue equivalents: a review

2021 ◽  
Author(s):  
Jonas F. Eichinger ◽  
Lea J. Haeusel ◽  
Daniel Paukner ◽  
Roland C. Aydin ◽  
Jay D. Humphrey ◽  
...  
Keyword(s):  
Multiple Scales ◽  
Experimental Studies ◽  
Biological Tissues ◽  
Future Research ◽  
Collagen Gels ◽  
Tissue Equivalents ◽  
Current State ◽  
Open Questions ◽  
Mechanical Homeostasis ◽  
State Of Research

AbstractThere is substantial evidence that growth and remodeling of load bearing soft biological tissues is to a large extent controlled by mechanical factors. Mechanical homeostasis, which describes the natural tendency of such tissues to establish, maintain, or restore a preferred mechanical state, is thought to be one mechanism by which such control is achieved across multiple scales. Yet, many questions remain regarding what promotes or prevents homeostasis. Tissue equivalents, such as collagen gels seeded with living cells, have become an important tool to address these open questions under well-defined, though limited, conditions. This article briefly reviews the current state of research in this area. It summarizes, categorizes, and compares experimental observations from the literature that focus on the development of tension in tissue equivalents. It focuses primarily on uniaxial and biaxial experimental studies, which are well-suited for quantifying interactions between mechanics and biology. The article concludes with a brief discussion of key questions for future research in this field.

High-frequency Oscillations in Epilepsy: What Have We Learned and What Needs to be Addressed

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000011465 ◽  
Author(s):  
Zhuying Chen ◽  
Matias I. Maturana ◽  
Anthony N. Burkitt ◽  
Mark J. Cook ◽  
David B. Grayden
Keyword(s):  
High Frequency ◽  
Future Research ◽  
Great Promise ◽  
Clinical Biomarkers ◽  
High Frequency Oscillations ◽  
Visual Identification ◽  
Current State ◽  
Open Questions ◽  
Term Data

For the past two decades, high-frequency oscillations (HFOs) have been enthusiastically studied by the epilepsy community. Emerging evidence shows that HFOs harbour great promise to delineate epileptogenic brain areas and possibly predict the likelihood of seizures. Investigations into HFOs in clinical epilepsy have advanced from small retrospective studies relying on visual identification and correlation analysis to larger prospective assessments using automatic detection and prediction strategies. While most studies have yielded promising results, some have revealed significant obstacles to clinical application of HFOs, thus raising debate about the reliability and practicality of HFOs as clinical biomarkers. In this review, we give an overview of the current state of HFO research and pinpoint the conceptual and methodological issues that have hampered HFO translation. We highlight recent insights gained from long-term data, high-density recordings and multicentre collaborations, and discuss the open questions that need to be addressed in future research.

scholarly journals Microbial Biomass Sulphur—An Important Yet Understudied Pool in Soil

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1606
Author(s):  
Stefanie Heinze ◽  
Michael Hemkemeyer ◽  
Sanja Annabell. Schwalb ◽  
Khalid Saifullah Khan ◽  
Rainer Georg Joergensen ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Soil Microbial Biomass ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Essential Elements ◽  
Future Research ◽  
Soil Microbial ◽  
Current State ◽  
Optimal Functioning ◽  
P Content

Soil microorganisms require a range of essential elements for their optimal functioning and store several elements in the microbial biomass (MB), such as carbon (C), nitrogen (N), phosphorus (P) and sulphur (S), as well as other secondary and trace elements. The C, N and P content of the microbial biomass has been quantified in many studies for many years, whereas S has been the focus only in a few studies, despite the availability of methods and the relevance of MBS for the S turnover in soils. To illustrate the relevance of MBS, this review aims at summarizing the current state of knowledge on the quantities of MBS in different soils, influencing environmental and agricultural management factors, methodological shortcomings, and prospects for soil microbial biomass research. Median MBS contents were 6.0 µg g−1 soil in arable, 7.6 µg g−1 soil in grassland, and 5.7 µg g−1 soil in forest soils. All extractants used led to similar MBS contents in soils with similar soil organic (SO) C contents. MBC and soil pH positively explained MBS, using multiple linear regression analysis. Median MB-C/S ratios increased in the order arable (55), grassland (85), and forest (135) soils. As the overall quantity of MBS data is still small, future studies are required to verify these observations. Moreover, future research needs to more strongly consider stoichiometric relationships of elements in the soil and the soil microbial ionome. The role of S and its complex relationship with the availability of other elements in soils for the soil microbial biomass and its functions remains to be elucidated.

scholarly journals Ultrastructural Changes of Hepatic Stellate Cells in the Space of Disse in Alcoholic Fatty Liver

2001 ◽  
Vol 16 (3) ◽  
pp. 160-166 ◽  
Author(s):  
Nam Ik Han ◽  
Kyu Won Chung ◽  
Byung Min Ahn ◽  
Sang Wook Choi ◽  
Young Sok Lee ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Hepatic Stellate Cells ◽  
Stellate Cells ◽  
Ultrastructural Changes ◽  
Alcoholic Fatty Liver ◽  
Space Of Disse

scholarly journals Hepatic Stellate Cell: A Double-Edged Sword in the Liver

2021 ◽  
pp. 821-829
Author(s):  
N. Luo ◽  
J. Li ◽  
Y. Wei ◽  
J. Lu ◽  
R. Dong
Keyword(s):  
Liver Fibrosis ◽  
Hepatic Stellate Cells ◽  
Stellate Cell ◽  
Normal Liver ◽  
Stellate Cells ◽  
Comprehensive Understanding ◽  
Fibrosis Progression ◽  
Liver Fibrogenesis ◽  
Fibrosis Regression ◽  
Space Of Disse

Hepatic stellate cells (HSCs) are located in the space of Disse, between liver sinusoidal endothelia cells (LSECs) and hepatocytes. They have surprised and excited hepatologists for their biological characteristics. Under physiological quiescent conditions, HSCs are the major vitamin A-storing cells of the liver, playing crucial roles in the liver development, regeneration, and tissue homeostasis. Upon injury-induced activation, HSCs convert to a pro-fibrotic state, producing the excessive extracellular matrix (ECM) and promoting angiogenesis in the liver fibrogenesis. Activated HSCs significantly contribute to liver fibrosis progression and inactivated HSCs are key to liver fibrosis regression. In this review, we summarize the comprehensive understanding of HSCs features, including their roles in normal liver and liver fibrosis in hopes of advancing the development of emerging diagnosis and treatment for hepatic fibrosis.

Sign in / Sign up

Export Citation Format

Share Document