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Gefühlte Dissonanz: Zur Entschädigung von NS-verfolgten Musikern in der frühen Bundesrepublik
No full textA Novel Approach to the Determination of Time- and Fatigue-Dependent Efficiency during Maximal Cycling Sprints
No full textBackground: During maximal cycling sprints, efficiency (η) is determined by the fiber composition of the muscles activated and cadence-dependent power output. To date, due to methodological limitations, it has only been possible to calculate gross efficiency (i.e., the ratio of total mechanical to total metabolic work) in vivo without assessing the impact of cadence and changes during exercise. Eliminating the impact of cadence provides optimal efficiency (ηopt), which can be modeled as a function of time. Here, we explain this concept, demonstrate its calculation, and compare the values obtained to actual data. Furthermore, we hypothesize that the time course of maximal power output (Pmax) reflects time-dependent changes in ηopt.
Methods: Twelve elite track cyclists performed four maximal sprints (3, 8, 12, 60 s) and a maximal-pedaling test on a cycle ergometer. Crank force and cadence were monitored continuously to determine fatigue-free force-velocity profiles (F/v) and fatigue-induced changes in Pmax. Respiratory gases were measured during and for 30 min post-exercise. Prior to and following each sprint, lactate in capillary blood was determined to calculate net blood lactate accumulation (ΔBLC). Lactic and alactic energy production were estimated from ΔBLC and the fast component of excess post-exercise oxygen consumption. Aerobic energy production was determined from oxygen uptake during exercise. Metabolic power (MP) was derived from total metabolic energy (WTOT). ηopt was calculated as Pmax divided by MP. Temporal changes in Pmax, WTOT, and ηopt were analyzed by non-linear regression.
Results: All models showed excellent quality (R2 > 0.982) and allowed accurate recalculation of time-specific power output and gross efficiency (R2 > 0.986). The time-constant for Pmax(t) (τP) was closely correlated with that of ηopt (τη; r = 0.998, p < 0.001). Estimating efficiency using τP for τη led to a 0.88 ± 0.35% error.
Conclusions: Although efficiency depends on pedal force and cadence, the latter influence can be eliminated by ηopt(t) using a mono-exponential equation whose time constant can be estimated from Pmax(t)
Über die soziale Arbeit in der Türkei: Essay über einen Besuch im Mai 2024 in Vereinen und bei staatlichen Institutionen in Ankara, Izmir und Istanbul mit dem CIF
No full textDer dienstliche Austausch mit den Akteur*innen der Sozialpädagogik in der Türkei war äußerst konstruktiv und überraschend. Es war weder mir noch den Kolleg*innen bekannt, in welch einem weit entwickelten Stadium die soziale Arbeit, die Lehre an den Hochschulen und die Forschung sich dort befinden. Das ermöglicht eine Zusammenarbeit in Lehre und Forschung mit einigen der Akteur*innen in unterschiedlichen Projekten. Das Wissen um den Forschungsstand dort möchte ich mittels diesem Essay mit allen anderen Interessierten teilen.:Inhalt 2
1 Vorwort 3
2 Council of International Fellowship 5
3 Die moderne Türkei und die Vorstellungen der Deutschen 7
3.1 Die Vorstellungen der Deutschen über die Türkei 7
3.2 Die Rolle Atatürks im türkischen Staat 7
4 Die Reise 11
4.1 Ankara 11
4.2 Izmir 14
4.3 Istanbul 16
5 Soziale Arbeit und soziale Einrichtungen in der Türkei 18
5.1 Hochschulen 18
5.2 Familienhilfe, Kinder- und Jugendschutz 21
5.3 Flüchtlingshilfe 33
5.4 Gendersensible Arbeit 51
5.5 Arbeit für und mit Menschen mit Behinderungen 62
5.6 Obdachlosenarbeit 69
5.7 Gerichtsbarkeit und Opferschutz 71
5.8 Politische Arbeit 75
6. Fazit 80
Danksagungen 81
Literaturverzeichnis 82
Abkürzungsverzeichnis 85
Tabellenverzeichnis 8
Characterisation and Quantification of Upper Body Surface Motions for Tidal Volume Determination in Lung-Healthy Individuals
No full textMeasurement of accurate tidal volumes based on respiration-induced surface movements of the upper body would be valuable in clinical and sports monitoring applications, but most current methods lack the precision, ease of use, or cost effectiveness required for wide-scale uptake. In this paper, the theoretical ability of different sensors, such as inertial measurement units, strain gauges, or circumference measurement devices to determine tidal volumes were investigated, scrutinised and evaluated. Sixteen subjects performed different breathing patterns of different tidal volumes, while using a motion capture system to record surface motions and a spirometer as a reference to obtain tidal volumes. Subsequently, the motion-capture data were used to determine upper-body circumferences, tilt angles, distance changes, movements and accelerations-such data could potentially be measured using optical encoders, inertial measurement units, or strain gauges. From these parameters, the measurement range and correlation with the volume signal of the spirometer were determined. The highest correlations were found between the spirometer volume and upper body circumferences; surface deflection was also well correlated, while accelerations carried minor respiratory information. The ranges of thorax motion parameters measurable with common sensors and the values and correlations to respiratory volume are presented. This article thus provides a novel tool for sensor selection for a smart shirt analysis of respiration
Mittelfristige funktionelle und radiologische Ergebnisse von Patient:innen mit einer Pfannenzementierung in eine fest verankerte Pfanne (Cup in Cup)
No full textHintergrund: Wird bei älteren Risikopatient:innen mit Hüft-Totalendoprothese ein Revisionseingriff erforderlich und ist die zementfreie Pfanne noch gut knöchern integriert, besteht die Möglichkeit zur Zementierung einer Dual Mobility Pfanne (DMC) nach Inlay-Entfernung. Neben der postoperativen Prävention einer erneuten Luxation ist ein Vorteil dieser Off-Label-Anwendung einer DMC, dass die alte Pfanne belassen und somit Knochensubstanz erhalten werden kann. Aus dieser Vorgehensweise resultiert auch eine geringere Operations (OP)-Dauer, was gerade für multimorbide Patientengruppen von Bedeutung ist.
Fragestellung: Da es bislang nur wenige Untersuchungen zu diesem Verfahren gibt, sollte ermittelt werden, ob die Zementierung einer DMC in eine fest knöchern verankerte Pfanne eine effektive Option für den Revisionseingriff bei Risikopatient:innen darstellt.
Methoden: In dieser retrospektive Kohortenstudie wurden 33 Fälle zwischen 2015 und 2020 eingeschlossen. Häufigste Indikationen waren Rezidivluxationen (42 %) und Periprothetische Femurfrakturen (PPF) (39 %). Weitere Indikationen waren Inlay-Verschleiß (9 %), (Pseudo- )Tumor (6 %) und Schaftlockerung (3 %). Das mittlere Patientenalter betrug 79 ± 7 Jahre, die mittlere Nachuntersuchungs (NU)-Zeit 28,5±17,3Monate. Zur NU waren 15Patient:innen verstorben und ein Patient Lost-to-Follow-Up. Die klinische Auswertung erfolgte für 17 und die radiologische Auswertung für 33 Patient:innen. Primärer Endpunkt war die Pfannenrevision aufgrund jedweder Ursache. Sekundärer Endpunkt war die Prothesenlockerung im Röntgenbild. Die Funktion des Hüftgelenks und die Lebensqualität der Patienten wurden als tertiärer Endpunkt zusammengefasst und mit Hilfe des HHS, WOMAC und UCLA erhoben.
Ergebnisse: Der mittlere ASA-Score zum Zeitpunkt des Revisionseingriffs betrug 2,8 ± 0,6. Die mittlere OP-Dauer belief sich auf 124 ± 52 min. In zwei Fällen kam es zur Re-Luxation (6 %, Wechsel auf Constrained Liner). Es zeigte sich eine aseptische Lockerung der DMC (3 %) sowie eine Konusschädigung (3 %). Weitere Revisionen waren erforderlich wegen einer PPF (3 %, ORIF) sowie einer Wundheilungsstörung (3 %, Implantat-erhaltende Wundrevision). Die mittleren Punktwerte der einzelnen Scores zur NU lagen bei 59 ± 22 (HHS), 60 ± 26 (WOMAC) und 4 ± 2 (UCLA). Insgesamt ergaben sich nach Auswertung der Röntgenbilder – abgesehen von der erwähnten Revision bei Pfannenausbruch – keine weiteren Anzeichen für Lockerungen oder Veränderungen der DMC-Position, sodass die Überlebensraten nach einer mittleren NU von 28,5 Monaten bei 86,8 % (n = 33) für den primären Endpunkt und bei 92,3 % (n = 22) für den sekundären Endpunkt lag.
Schlussfolgerung: Die Off-Label-Zementierung einer DMC in eine fest verankerte Pfanne weist kurz- bis mittelfristig eine geringe Lockerungs- sowie Gesamtkomplikationsrate auf. Ob das Verfahren auch bei längerer Beobachtungszeit gute Ergebnisse zeigt, müssen weitergehende Untersuchungen klären.Background: If a revision procedure is required in an elderly high-risk patient after a previous total hip arthroplasty and if the cementless acetabular cup is still well integrated in the bone, it is possible to insert a cemented Dual Mobility Cup (DMC) after removal of the inlay. In addition to the postoperative prevention of re-dislocation, this “off-label” application allows the old cup to be left in place. Therefore, bone substance can be preserved. It also usually results in a shorter Operation (OP) time, which is particularly important for this high-risk patient groups.
Objective: As there are only few studies on the success of this procedure so far, the aim is to determine whether cementing a DMC into a firmly anchored cup is an effective option for revision surgery in high-risk patients.
Methods: This retrospective cohort study included 33 patients between 2015 and 2020. The most common indications were recurrent dislocation (42 %) and periprosthetic fracture (39 %). Other indications were inlay wear (9 %), (pseudo-)tumour (6 %) and socket loosening (3 %). The mean patient age was 79 ± 7 years, and the mean follow-up (FU) time was 28.5 ± 17.3 months. At FU, 15 patients were deceased, and one patient was lost-to-follow-up. Data from 17 patients were available for the clinical evaluation and data from 33 patients for the radiological evaluation. The primary endpoint was revision of the inserted cup due to any cause. The secondary endpoint was prosthesis loosening as determined by the radiograph. The function of the hip joint and the quality of life of the patients were summarized as the tertiary endpoints and assessed using the HHS, WOMAC and UCLA.
Results: The mean ASA-score at the time of revision surgery was 2.8 ± 0.6 and the mean operative time was 124 ± 52 min. Re-dislocation occurred in two cases (6.1 %, conversion to a constrained liner). There was one aseptic loosening of the DMC construct (3.0 %) and one case of cone damage (3.0 %). Further revisions were required due to a periprosthetic fracture (3.0 %, open reduction with internal fixation) and a wound healing disorder (3.0 %, implant-preserving wound revision). The mean scores at FU were 59 ± 22 (HHS), 60 ± 26 (WOMAC) and 4 ± 2 (UCLA). Overall, after evaluation of the radiographs, there was no evidence of loosening or change in DMC position, apart from the aforementioned revision for acetabular loosening. Thus, the survival rate after the mean FU of 28.5 months was 86,8 % (n = 33) for the primary endpoint and 92,3 % (n = 22) for the secondary endpoint.
Conculsion: The “off-label” cementation of a DMC into a firmly anchored acetabular cup has a low loosening rate and a low overall complication rate in the short to medium term. Whether the procedure also shows good results over a longer observation period must be clarified in further studies
Entwicklung und Realisierung eines Ansatzes zur robotergestützten Sortierung chaotisch gelagerter Objekte
No full textIn immer flexibler werdenden Produktionsanlagen und -abläufen spielen Roboter aufgrund deren inheränter
Flexibilität eine entscheidende Rolle. Eine klassische Aufgabe in diesem Kontext ist die Vereinzellung
chaotisch gelagerter Teile (auch Bin-Picking genannt). In diesem Beitrag wird die Situation
betrachtet, in der die Modellfabrik der FH Münster mit zylindrischen Rohteile versorgt werden soll,
wobei diese Rohteile chaotisch gelagert, d. h. in beliebiger Orientierung, vorliegen. Dieser Beitrag präsentiert
ein Konzept sowie dessen Realisierung, um die Rohteile für die spätere Übergabe an die Modellfabrik
korrekt auszurichten. Das Konzept umfasst (1) die Erkennung der Lage der Rohteil basierend
auf Tiefenbildinformationen und (2) das Greifen der Objekte für die Umorientierung in die gewünschte
Lage. Die Implementierung des Konzeptes erfolgt in C++ unter Verwendung von des Robot Operating
Systems sowie der Point Cloud Library
From the ‘Theatre of the Tree’ to the Necrocity: Ngong Kum Ngong’s Poetic Vision in Blot on the Landscape
No full textDigital Transformation and Digital Inequality in Ghana, West Africa
No full textThe social implications of digital transformation in Ghana and other parts of Africa have not drawn much research attention despite the potential risks of digital change. This study assessed the state of digital transformation, the nature of digital inequality and the effects of digitization on digital inequality in Ghana. The study was carried out using the sequential explanatory mixed methodology. The researcher surveyed three thousand, one hundred and sixty-two (3162) people randomly selected from nine (9) administrative districts in Ghana's Savannah and Greater Accra regions. In addition, the researcher conducted in-depth personal interviews with six (6) purposively sampled key informants. This study revealed that Ghana is at the beginning stages of being digitally transformed. Mobile phones are widely available throughout the country, but computers are not as common. The available technologies are unevenly distributed. Digital transformation in Ghana is beginning to manifest in the structure of the Ghanaian economy, society, and government. However, there are persistent gender and geographic disparities in digital access, digital skills, and usages. Gendered digital inequalities are steeper than geographic disparities, and women in the Savannah region suffer the most digital disadvantages due to the interaction between gender and geography. Also, as the Internet becomes more widely available in Ghana, digital access gaps are closing but the digital skills and usage gaps are emerging, consistent with the tenets Resources and Appropriation theory. This study concludes that Ghana’s digital rapid transformation could exacerbate exiting social divides, especially gender inequalities if it is not operationalised and implemented more tactfully.:DEDICATION i
ACKNOWLEDGEMENT ii
ABBREVIATIONS iii
ABSTRACT v
TABLE OF CONTENT vi
LIST OF TABLES xiv
LIST OF FIGURES xvi
CHAPTER ONE 1
GENNERAL INTRODUCTION 1
1.1 Chapter Overview 1
1.2 Background to the study 1
1.2 Research Problem 4
1.3 Purpose of the study 6
1.4 Objectives of the Study 6
1.5 Research Questions 7
1.6 Significance of the study 7
1.7 Organization of the Study 8
CHAPTER TWO 9
DEFINITION OF KEY CONCEPTS 9
2.1 Chapter overview 9
2.2 Digitization 9
2.3 Digitalization 11
2.4 Digital Transformation 13
2.5 The Digital Divide 16
2.6 Evolution of the Digital Divide 19
2.7 From Digital Divide to Digital Inequality 22
2.8 Chapter Summary 24
CHAPTER THREE 25
DIGITAL INEQUALITY 25
3.1 Chapter overview 25
3.2 Digital Inequality 25
3.3 Forms of Digital Inequality 28
3.3.1 Inequality in technical means (access) 28
3.3.2 Inequality in Autonomy (control) 28
3.3.3 Inequality in Skills (Usage) 29
3.3.4 Inequality in Social support (Network) 30
3.3.5 Inequality in purpose of use (outcome) 30
3.4 Determinants of Digital Inequalities 31
3.4.1 Demographic determinants 32
3.4.2 Economic Determinants 34
3.4.3 Social Determinants 35
3.4.4 Cultural Determinants 36
3.4.5 Personal Determinants 37
3.4.6 Material Determinants 38
3.4.7 Motivational Determinants 38
3.4.8 Urban-rural dimension 39
3.5 Chapter Summary 40
CHAPTER FOUR 41
THEORETICAL UNDERPINNINGS OF THE STUDY 41
4.1 Chapter overview 41
4.2 The Social Construction of Technology (SCOT) 41
4.2.1 Evolution and Development of SCOT 41
4.2.2 Elements of SCOT 43
4.2.2.2 Interpretative flexibility 44
4.2.2.3 Stabilization and Closure 45
4.2.2.4 Technological Frame 46
4.2.2.5 Wider social context 47
4.2.3 Dichotomy between technology constructionism and determinism 48
4.2.4 Limitations of SCOT 49
4.2.5 SCOT Research 50
4.3 Resources and Appropriation Theory 52
4.3.1 Origins and development of Resources and Appropriation theory (RAT) 52
4.3.2 Central arguments and concepts of RAT 53
4.3.3 Technology Appropriation 55
4.3.4 Research on Technology Appropriation 59
4.3.5 Limitations of Resources and Appropriation theory 60
4.4 RAT and SCOT 61
4.5 Hypotheses Development 62
4.6 Chapter Summary 63
CHAPTER FIVE 64
DIGITAL TRANSFORMATION AND DIGITAL INEQUALITY IN AFRICA 64
5.1 Introduction 64
5.2 Digital Evolution in Sub-Saharan Africa 64
5.3 Africa’s Digital Agenda 66
5.4 Digital Transformation of Africa 71
5.5 The State of digital inequalities in Africa 75
5.6 Causes and Drivers of Digital Inequality in Africa 79
5.6.1 High incidence of poverty 79
5.6.2 Legacy inequalities 80
5.6.3 The dearth of basic ICT Infrastructure like electricity 81
5.6.4 Misguided ICT policies and weak regulation 83
5.6.5 Adverse digital incorporation 85
5.6.6 Covid-19 pandemic factor 87
5.6.7 Urbanism 88
5.7 Chapter Summary 89
CHAPTER SIX 90
COUNTRY CONTEXT: DIGITAL TRANSFORMATION IN GHANA 90
6.1 Chapter Overview 90
6.2 Why Ghana: Justifying the focus on Ghana 90
6.3 About Ghana: A Brief Country Profile 93
6.4 Ghana’s Digital Profile 95
6.5 Digital Transformation in Ghana 98
6.5.1 Digital transformation of businesses in Ghana 101
6.5.2 Digital transformation of society in Ghana 104
6.5.3 Digital Transformation of Government 107
6.6 Challenges and barriers to digital transformation in Ghana 110
6.7 Chapter Conclusion 115
CHAPTER SEVEN 117
RESEARCH METHODOLOGY 117
7.1 Introduction 117
7.2 Research Approach 117
7.3 Research Design 119
7.4 Measures 121
7.4.1 Construction of Indices 121
6.4.2 Major independent variables 124
7.5 Study Area 125
7.5.1 Study Area: Greater Accra Region 125
6.5.2 Study Area: Savanna Region 126
6.6 Study Population 128
6.7 Sampling Methods 129
6.7.1 Quantitative phase 129
7.7.2 Qualitative Phase 131
7.8 Data collection 132
7.8.1 Quantitative Phase: Questionnaire construction structure and content 133
7.8.2 Validity and Reliability 134
7.8.3 Questionnaire administration 135
7.8.4 Semi-structured in-depth interviews 136
7.9 Data Analysis 137
7.10 Research Ethics 138
7.11 Data Collection Challenges 140
7.12 Chapter Summary 141
CHAPTER EIGHT 142
FINDINGS AND ANALYSIS: DEMOGRAPHIC CHARACTERISTICS 142
8.1 Chapter Overview 142
8.2 Geographical Distribution 142
8.3 Sex Distribution of Respondents 144
8.4 Age Distribution 144
8.5 Educational Status of Respondents 146
8.6 Employment Status of Respondents 146
8.7 Ethnicity 148
8.8 Chapter Summary 149
CHAPTER NINE 150
FINDINGS AND ANALYSIS: STATE OF DIGITAL TRANSFORMATION IN GHANA 150
9.1 Chapter Overview 150
9.2 Digital Infrastructure 151
9.3 Digital Economy 153
9.4 Digital Government 155
9.5 Digital Society 157
9.6 Discussion of Findings 164
CHAPTER TEN 171
FINDINGS AND ANALYSIS: STATE OF DIGITAL INEQUALITY IN GHANA 171
10.1 Chapter Overview 171
10.2 Digital Access Divide (First level digital divide) 171
10.3 Digital Skills Divide (Second level digital divide) 182
10.4 Third-Level Digital Divide: Disparities in ICT usage 189
10.4.1 Frequency of internet use in the Greater Accra and Savannah Regions 190
10.4.2 Disparities in ICT Use in the Greater Accra and the Savannah Region 191
10.4.3 Frequency of internet use among females and males 194
10.4.4 Gender-based disparities in internet use 195
10.5 The Interaction of Gender, Geography and Digital inequality 198
10.6 Discussion of Findings 202
10.7 Chapter Summary 211
CHAPTER ELEVEN 212
FINDINGS & ANALYSIS: EFFECTS OF DIGITIZATION ON DIGITAL INEQUALITY IN GHANA 212
11.1 Chapter Overview 212
11.2 Effects of Internet availability on the digital access divide 212
11.3 Effects of Internet Availability on the Digital Skills divide 218
11.4 Effects of Internet availability on the digital usage 223
11.5 Chapter Summary 230
CHAPTER TWELVE 231
FINDINGS & ANALYSIS: IMPEDIMENTS TO DIGITAL TRANSFORMATION 231
12.1 Chapter Overview 231
12.2 Infrastructural Challenges 232
12.3 Operationalization and implementation of digitalization policies 234
12.4 High Cost of ICTs 237
12.5 Socio-cultural challenges 240
12.6 Digital Inequality 243
12.7 Cyber-security and privacy concerns 245
12.8 Low awareness and low patronage of government applications 248
12.9 Non-inclusion of vulnerable persons and groups 250
12.11 Chapter Summary 253
CHAPTER THIRTEEN 254
SUMMARY, CONCLUSION AND RECOMMENDATIONS 254
13.1 Chapter overview 254
13.2 Summary of the study 254
13.3 Conclusion 258
13.4 Recommendations: Towards a digital transformation strategy for Ghana 261
APPENDIXES 29
Ginpuin – Auf der Suche nach dem großen Glück: von Barbara van den Speulhof und Henrike Wilson, in einer Fassung von Winnie Karnofka, Puppentheater und Schauspiel, Sonnenhäusel im Großen Garten : 5+
No full textIn ihrem 2012 erschienenen Kinderbuch schildern Autorin
Barbara van den Speulhof und Illustratorin Henrike Wilson die
Reise eines Pinguins, der sich nicht unterkriegen lässt. Regisseur
Moritz Sostmann setzt diese Reise in seiner Inszenierung
im Zusammentreffen von Maskentheater, Schauspiel und
verschiedenen Formen von Handpuppen um.
Premiere So 02. Jun 201
Targeting the hyperglycemic memory in diabetic kidney disease is therapeutically amendable
No full textDespite medical advances in the last decades, diabetic kidney disease (DKD) remains a major therapeutic challenge. DKD, the major microvascular complication in diabetic patients, is the most common cause of chronic kidney disease (CKD) and end-stage kidney disease (ESKD) requiring dialysis worldwide. In recent years, new therapeutic approaches for the treatment of DKD in addition to stringent blood glucose control and inhibition of angiotensin-signaling have been established. These new therapeutic options include sodium glucose cotransporter-2 inhibitors (SGLT2i), GLP-1 agonists, and nonsteroidal mineralocorticoid receptor antagonists. Despite their promising positive outcomes regarding kidney function, their long-term effects through the course of the disease remain unknown. Additionally, recent data show that about 50% of patients with DKD do not respond to these new therapeutics even if given in combination and there is a lack of therapies that can reverse the already established DKD.
The continuous progression of diabetic complications (including DKD) despite normalization of blood glucose levels is referred to as the hyperglycemic memory. This phenomenon represents an unsolved medical problem in the field of diabetes management and remains without specific treatment options. Several theories have been proposed to explain the persistence of hyperglycemia-induced cellular dysfunction despite blood glucose normalization, and epigenetic regulation of gene expression has been proposed as the key pathomechanism driving the hyperglycemic memory. In this study, we used a combination of animal models, analyanalysesuman tissue and biofluid samples, in addition to in vitro mechanistic studies to identify therapeutically targetable pathways for the hyperglycemic memory in the context of DKD. To experimentally address the hyperglycemic memory, we used a model of hyperglycemia reversal in type-1 (STZ) and type-2 (db/db) diabetic mice. Hyperglycemia was reversed using SGLT2i (STZ and db/db mice) or insulin (STZ mice). We started by characterizing the functional and histological changes associated with hyperglycemic memory including persistent albuminuria, tubular hypertrophy, and fibrosis. To identify the pathways associated with the hyperglycemic memory in both models, we conducted bulk RNA sequencing from the kidneys and identified a large number of genes that were persistently up- or downregulated despite blood glucose normalization and hence possibly contributing to the hyperglycemic memory. Among these genes, we identified the cyclin-dependent kinase inhibitor p21 (Cdkn1a), which is known to regulate cellular senescence, as a primary candidate associated with the hyperglycemic memory, where its expression remained persistently upregulated despite blood glucose lowering in both diabetes models. Further investigations confirmed the “memorized” expression of p21 across DKD animal models and in cell lines in vitro, pinpointing the tubular epithelium as the specific cell type where this phenomenon occurs. Using a multimarker approach, we identified a persistent tubular senescence phenotype associated with p21 induction regardless of the intervention to reduce blood glucose levels in murine DKD models.
Subsequent analyses aimed to scrutinize the relevance of this finding in the context of human DKD. We found induction of tubular p21 expression and senescence in human DKD biopsies compared to controls or to diabetic patients without kidney dysfunction. Furthermore, p21 was readily detected in the urine of DKD patients in a large cross-sectional cohort whic,h was increased with the severity of the disease and was negatively correlated with kidney function. Interestingly, urinary p21 levels remained persistently elevated despite different interventions to reduce blood glucose levels (SGLT2i or fasting-mimicking diet), corroborating its utility as a biomarker for the hyperglycemic memory in DKD.
Next, we further elucidated the sequence of eventeventshyperglycemia to the induction of p21 and subsequent kidney damage, demonstrating that elevated blood glucose decreases DNA methyltransferase 1 (DNMT1) expression, resulting in hypomethylation of the p21 promoter and increased p21 expression. The induction of p21 expression triggers a senescence phenotype, that contributes to tubular damage and fibrosis. Suppression of tubular DNMT1 expression was sufficient to induce p21 in tubular cells, corroborating the importance of this epigenetic mechanism for the glucose-induced persistence of p21 expression.
In order to investigate possible translational implications, we studied the potential of reversing the hyperglycemic memory in DKD. We employed the cytoprotective protease activated protein C (aPC), a disease resolving mediator associated with DKD protection. aPC in conjunction with the blood glucose lowering drug SGLT2i induced the expression of DNMT1 leading to promoter remethylation and suppression of the persistent tubular p21 expression. Notably, SGLT2i alone had no effect on p21 expression. The combined action of SGLT2i and aPC effectively counteracted albuminuria, tubular damage, senescence, and fibrosis in a murine DKD model.
The protective effects of aPC were confirmed by investigating TMPro/Pro mice, in which thrombomodulin-mediated protein C activation is hampered resulting in reduced aPC levels. Induction of persistent hyperglycemia in these mice elevated p21 expression in association with aggravated kidney damage compared to wild-type mice. Superimposed deficiency of p21 in the aforementioned aPC-deficient mice (TMPro/Pro x p21-/-) alleviated the tubular injury and senescence phenotype, providing experimental in vivo evidence for a regulation of the hyperglycemic memory in DKD by the interaction of p21 by aPC levels.
To confirm that aPC regulates DNMT1 and hence p21 in an epigenetic manner, we targeted DNMT1 in aPC-treated mice using the pan DNMT inhibitor 5-aza-2'-deoxycytidine or a specific vivo morpholino against DNMT1. Both approaches abolished aPC’s protective effects in a murine DKD model and inhibited its ability to reduce p21 promoter hypomethylation and hence its expression. Exploiting the cytoprotective properties of aPC by using the mutant 3K3A-aPC, which lacks the anticoagulant ability, or the chemical compound parmodulin-2 that mimics the biased signaling of aPC via the G protein-coupled receptor PAR1, was enough to reduce the hyperglycemia-induced p21 expression and the associated tubular senescence in murine DKD.
The findings of this study uncover an important role of p21 in exacerbating renal damage under diabetic conditions, suggesting that p21 not only serves as a marker of cellular senescence but actively contributes to the persistence of DKD by mediating the hyperglycemic memory. By addressing the root causes of hyperglycemic memory, such as the epigenetic modifications that perpetuate p21 expression, it may be possible to halt or even reverse the progression of DKD. The feasibility of this approach was demonstrated by exploiting cytoprotective aPC signaling, which restored DNMT1 expression and reduced p21 expression. Thus, targeting the hyperglycemic memory in DKD may be feasible in general and may be specifically achieved by targeting cytoprotective aPC signaling.:Table of contents
Table of contents 2
List of figures 5
List of tables 6
List of abbreviations 7
1. Introduction 9
1.1 Diabetes mellitus 9
1.2 Diabetic complications 9
1.3 Diabetic kidney disease (DKD) 10
1.3.1 Clinical presentation and staging of DKD patients 10
1.3.2 Cellular dysfunction in DKD 12
1.4 The hyperglycemic memory: a new challenge in DM management 14
1.4.1 Hyperglycemic memory in DKD 14
1.4.2 Mechanisms of the hyperglycemic memory 18
1.5 Cellular senescence in DKD 20
1.5.1 Features of senescent cells in DKD 20
1.5.2 Tubular cell senescence in DKD 23
1.6 Therapeutic management of DKD 23
1.6.1 SGLT2 inhibitors 24
1.6.2 Other therapeutic options for DKD 25
1.7 Coagulation proteases and their receptors in DKD 26
1.7.1 Protease-activated receptors (PARs) 26
1.7.2 Activated protein C (aPC) 27
2. Aim of the study 32
3. Methods 33
3.1 Reagents 33
3.2 Mice and in vivo interventions 34
3.3 Cell culture and in vitro interventions 35
3.4 Human renal biopsies and urine samples 36
3.5 Glucose uptake assay 41
3.6 In vitro Knockdown 41
3.7 Preparation of activated protein C 42
3.8 Urine collection and processing 42
3.9 p21 ELISA for human urine samples 43
3.10 Albuminuria and in mouse urine samples 43
3.11 Methylation specific PCR (MSP) 43
3.12 Pyrosequencing 44
3.13 DNMT activity assay 44
3.14 Immunoblotting 45
3.15 Reverse transcriptase PCR (RT-PCR) 45
3.16 Quantitative real time PCR (qRT-PCR) 46
3.17 RNA expression profiling 48
3.18 Functional annotation and Pathway analysis 48
3.19 Histology, immunohistochemistry and histological analyses 49
3.20 Immunofluorescence 49
3.21 Senescence associated beta galactosidase (SA-β-gal.) staining 50
3.22 Plasma creatinine and blood urea nitrogen (BUN) 50
3.23 Cell cycle analysis 50
3.24 Statistical Analysis 51
4. Results 52
4.1 Blood glucose normalization does not reverse DKD in experimental models of DM 52
4.2 Identification of genes and pathways associated with hyperglycemic memory 54
4.3 Sustained renal tubular p21 induction in experimental DKD models despite blood glucose normalization 56
4.4 Tubular p21 induction is independent on glomerular damage 58
4.5 Sustained renal tubular p21 expression is associated with induction of senescence 59
4.6. Induction of renal tubular p21 expression in human DKD patients is associated with kidney dysfunction 61
4.7. Sustained p21 expression despite glucose normalization in human DKD patients 63
4.8 aPC reverses glucose induced p21 promoter methylation and sustained p21 expression 64
4.9 Impaired protein C activation increases tubular p21 expression and senescence in vivo 66
4.10 p21 mediates enhanced tubular senescence in aPC-deficient mice 68
4.11 High glucose differentially regulates renal DNMTs expression and activity 70
4.12 Hyperglycemia-induced DNMT1 suppression is part of the hyperglycemic memory 72
4.13 aPC reverses glucose-induced and sustained renal p21 expression via DNMT1 in vivo 74
4.14 aPC reverses glucose-induced and sustained renal tubular senescence via DNMT1 in vivo 76
4.15 aPC requires PAR1 and EPCR to regulate p21 expression 78
4.16 aPC regulates the epigenetically sustained p21 expression independent of its anticoagulant function in vivo 79
4.17 aPC enhances the regenerative capacity of DM kidneys after acute injury by reversing the hyperglycemic memory 81
5. Discussion 85
6. Future perspectives 92
7. Summary of the work 93
8. References 96
Declaration on the independent preparation of the dissertation 104
Curriculum Vitae 106
List of publications 107
Acknowledgement 109