Investigating complex I dynamics and ROS production in ischaemia-reperfusion injury

Ischaemia-reperfusion (IR) injury is caused paradoxically when the flow of oxygenated blood to an organ is restored after a period of restricted blood supply (ischaemia) in the course of a heart attack, stroke or organ transplantation. Mitochondria play a central role in the pathology of IR injury and are also at the heart of metabolism, which becomes dysregulated during ischaemia and causes formation of reactive oxygen species (ROS) when oxygen is resupplied. Complex I is a major source of ROS in IR injury, but also in physiological ROS signalling. The enzyme can produce ROS via reverse electron transfer (RET), which is driven by a large protonmotive force (∆p) in conjunction with a reduced coenzyme Q (CoQ) pool, with the required electrons deriving from succinate oxidation. ROS causes severe damage to cellular components, leading to cell death and ultimately to chronic inflammation. In order to expand our knowledge on the role and function of complex I in IR injury, I have developed a new mass spectrometry approach to characterise the reversible deactivation (active/deactive transition) of the complex based on the exposure of the critical Cys39 residue of its ND3 subunit. I confirmed that complex I gradually deactivates in the absence of turnover, in simplified in vitro model systems as well as during ischaemia in vivo. Conversely, reperfusion resulted in rapid reactivation of complex I. Further, declining complex I activity was found to inversely correlate with an increase in Cys39 exposure, which suggests a causal relationship. Beyond this, I developed a robust, sensitive and broadly applicable mass spectrometry-based method to determine the CoQ pool size and redox state in vivo. This method enabled me to explore the CoQ redox state during IR in heart. Remarkably, the CoQ pool appeared to be highly reduced in vivo, independent of the oxygen availability and metabolic changes throughout ischaemia. Finally, I explored RET derived ROS formation and its thermodynamic drivers in mitochondria and tissue from mice, harbouring a P25L point mutation within their ND6 subunit of complex I, which prevents the enzyme from performing RET. In a collaboration with the Hirst laboratory we combined cryoEM derived structural information from their lab with in vivo data from a myocardial infarction model that enabled us to identify the RET-blocking mechanism caused by this mutation and to confirm RET derived ROS as major cause for IR injury. In summary, my work provides new experimental tools and insights into the role and dynamics of complex I, RET-derived ROS production and its drivers during IR in vivo

Citizens4Citizens: mapping participatory practices on the internet

Many important forms of public participation take place in interactions between citizens. Studying these interactions is crucial for understanding e‑governance, defined as steering in the public domain. The new forms of public participations can be labeled Citizens2Citizens interactions (C2C). Citizens use the Internet to facilitate policy participation (meant to support or undermine government policies), political participation (directed at influencing political decision‑making and agenda‑setting) and social participation (to increase social capital). Attention for these forms of digital participation coincides with the rise of a new set of Web applications which are grouped under the label 'Web 2.0'. This paper is an attempt to conceptualize and categorize the wide variety of types and forms of C2C to provide a basis for a further development of this new research field. We do not claim that our exploration will lead to a final and complete description of C2C; we merely aim to present an overview of the diversity of forms of C2C initiatives that are taking place in the digital world. The argument we are putting forward is that new technologies offer new venues for participating and that these new practices will constitute both a replication of and an addition to existing offline practices of public participation. Our explorative research of C2C initiatives results in a map of political, policy and social participation. This map of C2C initiatives can provide insights in the variety of Internet practices and help subsequent researches in their selection of initiatives for in‑depth studies. Additionally, our research results in an exploration of the implications the analyzed initiatives can have for participation in the public sector

A sensitive mass spectrometric assay for mitochondrial CoQ pool redox state in vivo

Coenzyme Q (CoQ) is an essential cofactor, primarily found in the mitochondrial inner membrane where it functions as an electron carrier in the respiratory chain, and a lipophilic antioxidant. The redox state of the CoQ pool is the ratio of its oxidised (ubiquinone) and reduced (ubiquinol) forms, and is a key indicator of mitochondrial bioenergetic and antioxidant status. However, the role of CoQ redox state in vivo is poorly understood, because determining its value is technically challenging due to redox changes during isolation, extraction and analysis. To address these problems, we have developed a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay that enables us to extract and analyse both the CoQ redox state and the magnitude of the CoQ pool with negligible changes to redox state from small amounts of tissue. This will enable the physiological and pathophysiological roles of the CoQ redox state to be investigated in vivo

A sensitive mass spectrometric assay for mitochondrial CoQ pool redox state in vivo.

Coenzyme Q (CoQ) is an essential cofactor, primarily found in the mitochondrial inner membrane where it functions as an electron carrier in the respiratory chain, and as a lipophilic antioxidant. The redox state of the CoQ pool is the ratio of its oxidised (ubiquinone) and reduced (ubiquinol) forms, and is a key indicator of mitochondrial bioenergetic and antioxidant status. However, the role of CoQ redox state in vivo is poorly understood, because determining its value is technically challenging due to redox changes during isolation, extraction and analysis. To address these problems, we have developed a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay that enables us to extract and analyse both the CoQ redox state and the magnitude of the CoQ pool with negligible changes to redox state from small amounts of tissue. This will enable the physiological and pathophysiological roles of the CoQ redox state to be investigated in vivo

Ischemic preconditioning protects against cardiac ischemia reperfusion injury without affecting succinate accumulation or oxidation.

Ischemia-reperfusion (IR) injury occurs when blood supply to an organ is disrupted and then restored, and underlies many disorders, notably myocardial infarction and stroke. While reperfusion of ischemic tissue is essential for survival, it also initiates cell death through generation of mitochondrial reactive oxygen species (ROS). Recent work has revealed a novel pathway underlying ROS production at reperfusion in vivo in which the accumulation of succinate during ischemia and its subsequent rapid oxidation at reperfusion drives ROS production at complex I by reverse electron transport (RET). Pharmacologically inhibiting ischemic succinate accumulation, or slowing succinate metabolism at reperfusion, have been shown to be cardioprotective against IR injury. Here, we determined whether ischemic preconditioning (IPC) contributes to cardioprotection by altering kinetics of succinate accumulation and oxidation during IR. Mice were subjected to a 30-minute occlusion of the left anterior descending coronary artery followed by reperfusion, with or without a protective IPC protocol prior to sustained ischemia. We found that IPC had no effect on ischemic succinate accumulation with both control and IPC mice having profound increases in succinate compared to normoxia. Furthermore, after only 1-minute reperfusion succinate was rapidly metabolised returning to near pre-ischemic levels in both groups. We conclude that IPC does not affect ischemic succinate accumulation, or its oxidation at reperfusion

Disruption of the TCA cycle reveals an ATF4-dependent integration of redox and amino acid metabolism.

The Tricarboxylic Acid (TCA) Cycle is arguably the most critical metabolic cycle in physiology and exists as an essential interface coordinating cellular metabolism, bioenergetics, and redox homeostasis. Despite decades of research, a comprehensive investigation into the consequences of TCA cycle dysfunction remains elusive. Here, we targeted two TCA cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDH), and combined metabolomics, transcriptomics, and proteomics analyses to fully appraise the consequences of TCA cycle inhibition (TCAi) in murine kidney epithelial cells. Our comparative approach shows that TCAi elicits a convergent rewiring of redox and amino acid metabolism dependent on the activation of ATF4 and the integrated stress response (ISR). Furthermore, we also uncover a divergent metabolic response, whereby acute FHi, but not SDHi, can maintain asparagine levels via reductive carboxylation and maintenance of cytosolic aspartate synthesis. Our work highlights an important interplay between the TCA cycle, redox biology, and amino acid homeostasis

Disruption of the TCA cycle reveals an ATF4-dependent integration of redox and amino acid metabolism.

The Tricarboxylic Acid (TCA) Cycle is arguably the most critical metabolic cycle in physiology and exists as an essential interface coordinating cellular metabolism, bioenergetics, and redox homeostasis. Despite decades of research, a comprehensive investigation into the consequences of TCA cycle dysfunction remains elusive. Here, we targeted two TCA cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDH), and combined metabolomics, transcriptomics, and proteomics analyses to fully appraise the consequences of TCA cycle inhibition (TCAi) in murine kidney epithelial cells. Our comparative approach shows that TCAi elicits a convergent rewiring of redox and amino acid metabolism dependent on the activation of ATF4 and the integrated stress response (ISR). Furthermore, we also uncover a divergent metabolic response, whereby acute FHi, but not SDHi, can maintain asparagine levels via reductive carboxylation and maintenance of cytosolic aspartate synthesis. Our work highlights an important interplay between the TCA cycle, redox biology, and amino acid homeostasis

Selective mitochondrial superoxide generation in vivo is cardioprotective through hormesis

Reactive oxygen species (ROS) have an equivocal role in myocardial ischaemia reperfusion injury. Within the cardiomyocyte, mitochondria are both a major source and target of ROS. We evaluate the effects of a selective, dose-dependent increase in mitochondrial ROS levels on cardiac physiology using the mitochondria-targeted redox cycler MitoParaquat (MitoPQ). Low levels of ROS decrease the susceptibility of neonatal rat ventricular myocytes (NRVMs) to anoxia/reoxygenation injury and also cause profound protection in an in vivo mouse model of ischaemia/reperfusion. However higher doses of MitoPQ resulted in a progressive alteration of intracellular [Ca2+] homeostasis and mitochondrial function in vitro, leading to dysfunction and death at high doses. Our data show that a primary increase in mitochondrial ROS can alter cellular function, and support a hormetic model in which low levels of ROS are cardioprotective while higher levels of ROS are cardiotoxic.The work is supported by an MRC Studentship to JFM and a Wellcome Trust Investigator award to RCH (110158/Z/15/Z), the Leducq Transatlantic Network of Excellence, and the University of Padova Strategico grant (FDL). Part of the study was funded by an MRC Project Grant to TK (MR/P000320/1). Michele Cariello is thanked for help with cyclic voltammetry

dolls/puppets in threat scenarios

Puppen in Bedrohungsszenarien – so lautet der Themenschwerpunkt der ersten Ausgabe der interdisziplinären online-Zeitschrift "denkste: puppe / just a bit of: doll" zu Mensch-Puppen-Diskursen (Akronym: de:do). Die Bezeichnung ‚Puppe’ steht dabei für anthropomorphe ,Wesen’ und Artefakte in all ihren unterschiedlichen Erscheinungsformen und der Begriff der Bedrohung wird hier weit gefasst. Ausgangspunkt der Entscheidung für diesen Fokus war die Annahme, dass Puppen und puppenaffinen Artefakten sowohl in Zeiten existenzieller Bedrohung als auch in Phasen innerpsychischer Beunruhigung und Irritation eine besondere Bedeutung zukommt. Die hier einbezogenen Beiträge stammen aus unterschiedlichen Fachdisziplinen und eröffnen in der bewusst nicht disziplinär ausgerichteten Zusammenstellung reizvolle multiperspektivische Mensch-Puppen-Diskurse. Dabei sind nicht nur die hier angesprochenen Themenbezüge, sondern auch die jeweiligen methodischen Zugänge ausgesprochen heterogen. So werden Puppen-Narrative aufgegriffen, die beispielsweise innerhalb der Literaturwissenschaft an die lange Tradition von Puppen-Erzählungen anknüpfen, aber auch solche, die aktuell in den Diskursen über Zukunftsszenarien und neue Technologien mittels verschiedener medialer Formate und/oder künstlerischer Aktionen für Diskussionsstoff sorgen. Ein erster thematischer Fokus liegt auf der Bedeutung von Puppen im Zuge der Erfahrung von Bedrohung und Verlusten im Kontext von Krieg, Flucht und Verfolgung in politisch unsicheren Zeiten. Hier werden aus verschiedenen fachdisziplinären Perspektiven unterschiedliche Facetten von Bedrohungsszenarien angesprochen. So geht es aus theaterwissenschaftlicher Sicht um zwei Inszenierungen aus dem Bereich des Objekt- und Materialtheaters, in denen bedrohliche Kriegsdarstellungen mittels Plastikpuppen bzw. amorphen Materials aufbereitet werden. Aus psychologischer Perspektive kommen Rollen und Funktionen von Puppen als Übergangsobjekte im Kontext von Umbrüchen, Krieg und Gewalt zur Sprache. In zwei literaturwissenschaftlichen Beiträgen wird jeweils ein Roman aus der Kinder- und Jugendliteratur analysiert, in denen in einem Fall eine Puppe zur psychischen Stabilisierung der literarischen Protagonistin beiträgt und im anderen Fall das Schicksal der Puppe die Geschichte von Abschied und letztendlicher Vernichtung ihrer Besitzerin erzählt und symbolisiert. Und schließlich geht es um den Stellenwert von Puppen und Teddys in verschiedenen Kinderzeitschriften, die – in den politisch unsicheren Zeiten zwischen und nach den beiden Weltkriegen – Identifikationsfiguren und Interaktionspartner für Kinder sein können. Ein zweiter Fokus thematisiert Puppen und ihre Narrative im Kontext verschiedener aversiver Erfahrungen sowie in Zeiten psychischer Irritation. So geht es zum einen um die literaturwissenschaftliche Sicht auf die Bedeutung und Wirkung von Puppen in zwei ‚klassischen’ Puppenerzählungen: „"Nussknacker und Mausekönig" von E.T.A. Hoffmann und "Romeo und Julia auf dem Dorfe" von Gottfried Keller. Zum anderen werden in verschiedenen Beiträgen Entgrenzungs-, Transformations- und Identitätsfragen in Mensch-Puppen-Bezügen aus medien- und kunstwissenschaftlicher sowie kinderliterarischer Perspektive angesprochen, in denen Puppen in Gestalt von Androiden, Kunstwesen oder anthropomorphen Figuren agieren und dabei selber Irritationen auslösen oder Versuche darstellen, Antworten auf beunruhigende Fragen zu finden. Über den Themenschwerpunkt hinaus finden sich zudem eine Reihe weiterer Beitragsformen zu verschiedenen puppenbezogenen Themen und Praxen, die noch einmal das breite Spektrum unterschiedlicher Puppen-Narrative und Zugangsformen dokumentieren: So beschäftigt sich ein freier Beitrag mit dem Puppenspiel als strukturiertes Therapieangebot für Kinder, bei den Miszellen findet sich eine Skizze zu Marlene Dietrich und ihren Puppen sowie ein kurzer Essay zu einer biographischen Erinnerung, ein Interview mit der Begründerin des Berliner Puppentheaters bubales veranschaulicht Möglichkeiten der dramatischen und poetischen Umsetzung von Puppen-Themen, im Diskussionsforum wird ein kritischer Blick auf "Barbie als Diskursmaschine" geworfen und eine Rezension zum Ausstellungskatalog "From Her Wooden Sleep von Ydessa Hendels" lotet Chancen und Grenzen der künstlerischen Arbeit mit Puppen-Artefakten aus.Dolls / Puppets in Threat Scenarios – this is the topic focus of the first issue of the interdisciplinary online magazine "denkste: puppe / just a bit of: doll" on human-doll discourses (acronym: de: do). The term ’doll’ stands for anthropomorphic ’beings’ and artifacts of all kinds and the concept of threat is broadly defined. This focus was stimulated by the assumption that dolls and doll-related artifacts are of particular importance in times of existential threat as well as in phases of inner psychic anxiety and irritation. Yet, the basically ambiguous character of the doll does not necessarily determine a clear effect, so that its usability always involves a certain blurriness and ambivalence. In threatening and adverse situations dolls can act as companions and significant (transitional) objects, thus allowing psychic stabilization, security, and attachment as well as enabling (inner) autonomy, agency, and developmental processes. But dolls can also be a crucial component of threat scenarios themselves and act frightening in this function. All this applies not only to material and real existing dolls and puppets, but also to dolls as literary and / or media figures as well as to doll narratives of any kind. The articles included here come from different disciplines and open up an appealing and deliberately non-disciplinary oriented human-doll discourse from multiple perspectives. Accordingly, the relevant themes as well as the respective methodological approaches are highly heterogeneous. Thus, some contributions follow the long tradition of doll narratives in literature while others discuss currrent topics and discourses on future scenarios and new technologies by means of various doll-related media formats and / or art performances. A first thematic focus is on the significance of dolls in experiencing threats and losses in the context of war, flight and persecution in times of political uncertainty. Here, different facets of threat scenarios are addressed from different disciplinary perspectives. From the field of object and material theater two productions are introduced in which menacing war scenes are processed by means of plastic dolls or amorphous material. From a psychological perspective, dolls are discussed in their roles and functions as transitional objects within the context of upheaval, war and violence. Furthermore, two literary contributions analyze novels from children’s and youth literature. One story deals with a doll which contributes to the psychological stabilization of the literary protagonist. The other story tells of a girl and her doll which symbolizes the final farewell and eventual annihilation of the (Jewish) girl. Finally, the role of dolls and teddy bears in various children’s magazines is exemplified, which serve as identification figures and interaction partners for children in the politically unstable times between and after the two World Wars. A second focus deals with dolls and their narratives in the context of various aversive experiences as well as in times of psychological irritation. Two contributions analyze the meaning and effect of dolls in two ’classical’ doll narratives from a literary perspective: "Nussknacker und Mausekönig" by E.T.A. Hoffmann and "Romeo und Julia auf dem Dorfe" by Gottfried Keller. Further contributions address questions of ego dissolution, transformation and identity processes in human-doll relations from various perspectives such as media, art and children’s literature. Here, dolls appear as androids, artistic or anthropomorphic figures which cause irritation themselves or attempt to find answers to disturbing human-doll questions. In addition to the main topic, there are also a number of other sections and types of contributions on various doll-related topics and practices which once again document the wide range of doll narratives and possible forms of access: For example, a free contribution deals with doll play as a structured therapy for children, the miscellaneous section includes a portrait of Marlene Dietrich and her dolls as well as a short essay on a biographical reminiscence, an interview with the founder of the Berlin Puppet Theater bubales illustrates the possibilities of dramatic and poetic realization of puppet and doll narratives, a critical view on "Barbie as a discourse machine" is presented in the discussion forum and a review of the exhibition catalog "From Her Wooden Sleep by Ydessa Hendels" explores opportunities and limits of artistic work with doll artifacts

Empirisch abgeleitete Empfehlungen für den Auf- und Ausbau von Tageshospizen in Deutschland – Ergebnisse einer Delphi-Befragung mit Expert:innen

Introduction: A needs-based and patient-oriented hospice and palliative care also includes day hospices as a specialised semi-inpatient care offer. The establishment and development of these facilities in Germany has been rather unsystematic. In order to ensure quality and adequacy of these structures, research is needed. Methods: A Delphi consensus study was conducted online from November 2022 to February 2023 aiming at generating recommendations for the development and expansion of day hospices in Germany. For each recommendation, the participants indicated on a four-point verbal rating scale how much they agreed upon a) the relevance and b) the feasibility of the recommendation. Items were considered consented when 80 % of the participants (strongly) agreed with the recommendation regarding both criteria. If no consensus was reached, the recommendations were revised according to the participants’ free text comments and presented in the next Delphi round. Descriptive analyses were applied. Results: A total of 64 experts participated in the first Delphi round and 44 in the second. In round 1, 34 recommendations and in round 2 six recommendations were consented. The final set contains a total of 40 recommendations: 18 on the tasks of day hospices, 13 on cooperation, 7 on funding, and 2 on public relations. Discussion: Recommendations for the development and expansion of day hospices in Germany were developed. Due to their highly rated feasibility, the recommendations should be directly transferable into care practice. It remains to be seen to what extent they will be taken into account in the renegotiation of the framework agreement for day hospices. Conclusion: The Delphi-consented recommendations provide a basis to guide action in the currently very dynamic development of hospice work and palliative care in Germany.Hintergrund: Zu einer bedarfsgerechten, patient:innenenorientierten Hospiz- und Palliativversorgung zählen auch Tageshospize als spezialisierte ambulante Versorgungsangebote. Aufbau und Entwicklung von Tageshospizen in Deutschland erfolgten bislang individuell und eigeninitiativ. Zur langfristigen Sicherstellung der Qualität und Bedarfsangemessenheit von Tageshospizen bedarf es wissenschaftlicher Erkenntnisse und Grundlagen. Methode: Von November 2022 bis Februar 2023 erfolgte eine deutschlandweite Online-Delphi-Befragung mit Expert:innen, in der Empfehlungen für den Auf- und Ausbau von Tageshospizen in Deutschland konsentiert wurden. Teilnehmende gaben zu jeder Empfehlung auf einer vierstufigen Rangskala an, wie sehr sie a) der Relevanz der Empfehlung und b) der Umsetzbarkeit der Empfehlung im Versorgungsalltag (nicht) zustimmen. Konsens wurde erreicht, wenn 80 % der Teilnehmenden einer Empfehlung in beiden Kriterien (eher) zustimmten. Wurde kein Konsens erreicht, wurden die Empfehlungen basierend auf Freitextkommentaren der Teilnehmenden angepasst und in der darauffolgenden Runde erneut zur Abstimmung gestellt. Die Analysen erfolgten deskriptiv. Ergebnisse: An der ersten Befragungsrunde beteiligten sich 64 und an der zweiten 44 Expert:innen. In Runde 1 wurden 34 und in Runde 2 sechs Empfehlungen konsentiert. Das finale Set enthält insgesamt 40 Empfehlungen: 18 zu Aufgaben, 13 zur Zusammenarbeit, 7 zur Finanzierung und 2 zur Öffentlichkeitsarbeit von Tageshospizen. Diskussion: Es konnten konkrete Empfehlungen zum Auf- und Ausbau von Tageshospizen in Deutschland entwickelt werden. Die Empfehlungen sollten aufgrund ihrer hoch bewerteten Umsetzbarkeit direkt in die Versorgungspraxis überführbar sein. Inwiefern die Empfehlungen in der Neuverhandlung der Rahmenvereinbarung für Tageshospize berücksichtigt werden, gilt es abzuwarten. Schlussfolgerung: Die vorliegenden Empfehlungen können handlungsweisend bei der aktuell sehr dynamischen Weiterentwicklung der Hospizarbeit und Palliativversorgung in Deutschland genutzt werden