Schlüsselfunktion der Mitochondrien in der Pathogenese der Alzheimer-Demenz

Die Alzheimer-Demenz (AD) ist gekennzeichnet durch extrazelluläre Ablagerungen des Amyloid-beta-Peptids (Aß), durch neurofibrilläre Bündel bestehend aus dem Tau-Protein, massiven Neuronenverlust und synaptische Dysfunktion. Weiterhin ist bekannt, dass mitochondriale Dysfunktion sowie ein gestörter NO-Stoffwechsel eine entscheidende Rolle bei der AD spielen. Um genauere Informationen über die Ursache der mitochondrialen Dysfunktion zu erhalten, wurden akute, chronische und dosisabhängige Effekte von Aß auf die NO-Produktion und die mitochondriale Funktion untersucht. Als Zellkulturmodelle standen PC12- und HEK-Zellen zur Verfügung, die entweder mit humanem Wildtyp-APP (APPwt) oder mit der schwedischen Doppelmutation im APP-Gen (APPsw) stabil transfiziert waren. APPsw-PC12-Zellen wiesen Aß-Spiegel im pikomolaren Bereich auf. Im Vergleich dazu hatten APPsw-HEK-Zellen ca. 20fach erhöhte Aß-Spiegel im niedrig-nanomolaren Bereich. Interessanterweise wiesen sowohl APPsw-PC12- als auch APPsw-HEK-Zellen im Vergleich zu den jeweiligen Kontrollzellen signifikant erhöhte NO-Spiegel auf. Dies ging in beiden Zellsystemen mit signifikant erniedrigten ATP-Spiegeln einher. Die Inkubation untransfizierter Zellen mit extrazellulärem Aß1-42 führte nur zu einem schwachen Anstieg der NO-Spiegel und zu einem leichten Abfall der ATP-Spiegel. Dies weist darauf hin, dass in erster Linie intrazelluläre Aß-Effekte den NO-Anstieg und die ATP-Reduktion bewirken. Die 48-stündige Inkubation mit dem gamma-Sekretasehemmstoff DAPT führte zur beinahe vollständigen Normalisierung der NO- und ATP-Spiegel in APP-transfizierten PC12- und HEK-Zellen. Das stützt die Hypothese, dass der gestörte NO-Stoffwechsel und die mitochondriale Dysfunktion durch Aß-Anreicherungen hervorgerufen werden und nicht durch eine Überexpression von APP. Passend zu den reduzierten ATP-Spiegeln zeigten APPsw-PC12-Zellen eine signifikant erniedrigte Cytochrom-C-Oxidase-Aktivität. Des Weiteren konnte APP in Mitochondrien von APPsw-PC12-Zellen nachgewiesen werden. Die Reduktion der ATP-Spiegel und die verminderte Cytochrom-C-Oxidase-Aktivität können also zum einen durch die Aß-bedingten erhöhten NO-Spiegel und zum anderen durch die Anwesenheit von APP bzw. Aß im Mitochondrium hervorgerufen werden. Auf der Ebene des mitochondrialen Membranpotentials wiesen die beiden Zelllinien stark unterschiedliche Ergebnisse auf. APPsw-PC12-Zellen zeigten unter basalen Verhältnissen ein leicht hyperpolarisiertes mitochondriales Membranpotential, was auf einen Gegenregulationsmechanismus hinweist. APPsw-HEK-Zellen wiesen bereits basal ein signifikant erniedrigtes mitochondriales Membranpotential auf. Nach Inkubation mit dem gamma-Sekretasehemmstoff DAPT normalisierte sich sowohl die Hyperpolarisation des mitochondrialen Membranpotentials in APPsw-PC12-Zellen als auch die Depolarisation in APPsw-HEK-Zellen. Anhand der in dieser Arbeit gewonnenen Daten konnte ein Modell sowohl für die sporadische als auch für die familiäre AD entwickelt werden. APPsw-PC12-Zellen spiegeln hierbei die pathogenen Mechanismen in Patienten mit sporadischer AD wider, wohingegen APPsw-HEK-Zellen die initialen Veränderungen bei Patienten mit familiärer AD aufzeigen. Mitochondriale Fehlfunktion und ein gestörter NO-Stoffwechsel stellen entscheidende initiale Pathomechanismen bei AD dar. Innerhalb der Gruppe der Antidementiva konnte gezeigt werden, dass sowohl Ginkgo-biloba-Extrakt als auch Piracetam schützende Effekte auf die mitochondriale Funktion ausüben. Aufgrund der wichtigen Rolle von mitochondrialer Fehlfunktion in der Pathogenese der Alzheimer Demenz stellen Ginkgo-biloba-Extrakt und Piracetam zwei sehr interessante Präventions- und Therapieoptionen bei Patienten mit leichten kognitiven Störungen bzw. bei Patienten mit AD dar

Effects of EGb 761® Ginkgo biloba extract on mitochondrial function and oxidative stress

As major sources of reactive oxygen species (ROS), mitochondrial structures are exposed to high concentrations of ROS and may therefore be particularly susceptible to oxidative damage. Mitochondrial damage could play a pivotal role in the cell death decision. A decrease in mitochondrial energy charge and redox state, loss of transmembrane potential (depolarization), mitochondrial respiratory chain impairment, and release of substances such as calcium and cytochrome c all contribute to apoptosis. These mitochondrial abnormalities may constitute a part of the spectrum of chronic oxidative stress in Alzheimer's disease. Accumulation of amyloid beta (Abeta) in form of senile plaques is also thought to play a central role in the pathogenesis of Alzheimer's disease mediated by oxidative stress. In addition, increasing evidence shows that Abeta generates free radicals in vitro, which mediate the toxicity of this peptide. In our study, PC12 cells were used to examine the protective features of EGb 761(definition see editorial) on mitochondria stressed with hydrogen peroxide and antimycin, an inhibitor of complex III. In addition, we investigated the efficacy of EGb 761 in Abeta-induced MTT reduction in PC12 cells. Moreover, we examined the effects of EGb 761 on ROS levels and ROS-induced apoptosis in lymphocytes from aged mice after in vivo administration. Here, we will report that EGb 761 was able to protect mitochondria from the attack of hydrogen peroxide, antimycin and Abeta. Furthermore, EGb 761 reduced ROS levels and ROS-induced apoptosis in lymphocytes from aged mice treated orally with EGb 761 for 2 weeks. Our data further emphasize neuroprotective properties of EGb 761, such as protection against Abeta-toxicity, and antiapoptotic properties, which are probably due to its preventive effects on mitochondria

Development and evaluation of a patient education programme for children, adolescents, and young adults with differences of sex development (DSD) and their parents: study protocol of Empower-DSD

Background: Differences in sexual development (DSD) are rare diseases, which affect the chromosomal, anatomical or gonadal sex differentiation. Although patient education is recommended as essential in a holistic care approach, standardised programmes are still lacking. The present protocol describes the aims, study design and methods of the Empower-DSD project, which developed an age-adapted multidisciplinary education programme to improve the diagnosis-specific knowledge, skills and empowerment of patients and their parents. Methods: The new patient education programme was developed for children, adolescents and young adults with congenital adrenal hyperplasia, Turner syndrome, Klinefelter syndrome or XX-/or XY-DSD and their parents. The quantitative and qualitative evaluation methods include standardised questionnaires, semi-structured interviews, and participatory observation. The main outcomes (assessed three and six months after the end of the programme) are health-related quality of life, disease burden, coping, and diagnosis-specific knowledge. The qualitative evaluation examines individual expectations and perceptions of the programme. The results of the quantitative and qualitative evaluation will be triangulated. Discussion: The study Empower-DSD was designed to reduce knowledge gaps regarding the feasibility, acceptance and effects of standardised patient education programmes for children and youth with DSD and their parents. A modular structured patient education programme with four generic and three diagnosis-specific modules based on the ModuS concept previously established for other chronic diseases was developed. The topics, learning objectives and recommended teaching methods are summarised in the structured curricula, one for each diagnosis and age group. At five study centres, 56 trainers were qualified for the implementation of the training programmes. A total of 336 subjects have been already enrolled in the study. The recruitment will go on until August 2022, the last follow-up survey is scheduled for February 2023. The results will help improve multidisciplinary and integrated care for children and youth with DSD and their families. Trial registration: German Clinical Trials Register, DRKS00023096. Registered 8 October 2020 - Retrospectively registered

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity

comparison between East and West and population based comparison

Titelblatt, Inhaltsverzeichnis, Abbildungs- u. Tabellenverzeichnis IV. Vorwort VI V. Abstract VIII VI. Einleitung 1 VII. Methode 9 VIII. Ergebnisse 27 IX. Diskussion 59 X. Zusammenfassung 102 XI. Summary 105 XII. Danksagung 108 XIII. Literaturverzeichnis 109 XIV. Anhang 132 XV. Lebenslauf 134Im Herbst 2000 wurde eine repräsentative schriftliche Befragung zur Erfassung der Lebensqualität der Berliner AllgemeinärztInnen mit dem SF-36 durchgeführt, einem international standardisierten Messinstrument, das Vergleiche ermöglicht. Die erhobenen Werte wurden mit denen der deutschen Bevölkerung verglichen und darüber hinaus auf Ost-West-Unterschiede untersucht. Es zeigte sich, dass die von der untersuchten Ärzteschaft erzielten Lebensqualitätswerte signifikant tiefer lagen als die Werte der bundesdeutschen Vergleichspopulation. Auf den vier psychischen Dimensionen des SF-36 war dieses schlechte Abschneiden der Ärzte noch stärker ausgeprägt als auf den vier körperlichen Dimensionen. Im Ost-West-Vergleich schnitten die Ostberliner ÄrztInnen besser ab als ihre Westberliner Kolleginnen und Kollegen. Als Erklärungsmöglichkeit kommt die aus der anderen Sozialisation resultierende Ausbildung anderer Werte in Betracht.In autumn 2000 we conducted a representative postal survey measuring quality of life in Berlins general practitioners using the SF-36, an internationally standardized tool, thus allowing comparisons. The results obtained were compared to those of the German population and moreover differences between East and West were explored. The Berlin GP population scored significantly poorer on the qol-scale than the German comparative population. On the four mental subscales of the SF-36 these low scores were even more salient than on the physical dimensions. These low scores are most likely to be caused by the stresses inherent to the medical profession, to wit financial constraints, time shortage and poor public reception of the medical profession. The fact that physicians are prone to impaired mental health anyway even aggravates the impact of the above mentioned factors. The East Berliner subgroup scored markedly better on the mental scales than the westerners. This is most likely to be caused by a different socialization, and consequently a different focus of values

New hospital buildings in Germany. Volume 1: General hospital and health centres

301 p.: illus.; 31 c

Stabilization of mitochondrial membrane potential and improvement of neuronal energy metabolism by Ginkgo biloba extract EGb 761

Ginkgo biloba extract EGb 761 has been used for many years to treat age-related cognitive disorders including Alzheimer's disease. EGb 761 given shortly after initiating mitochondrial damage by sodium nitroprusside (nitric oxide donor) improved the mitochondrial membrane potential of PC12 cells significantly and dose dependently. Under these conditions, EGb 761 also reversed the decrease in ATP production. In addition, similar protection against oxidative damage was found in dissociated brain cells and isolated brain mitochondria after in vitro or in vivo treatment with EGb 761. Moreover, PC12 cells bearing an Alzheimer's disease-related mutation in the amyloid precursor protein, which leads to enhanced beta amyloid production, showed greater benefit from treatment with EGb 761 than did control cells. Taken together, our findings clearly show stabilization and protection of mitochondrial function as a specific and very sensitive property of EGb 761 at therapeutically relevant doses

Increased apoptotic cell death in sporadic and genetic Alzheimer's disease

Mounting evidence indicates increased susceptibility to cell death and increased oxidative damage as common features in neurons from sporadic Alzheimer's disease (AD) patients but also from familial AD (FAD) cases. Autosomal dominant forms of FAD are caused by mutations of the amyloid precursor protein (APP) gene and by mutations of the genes encoding for presenilin 1 or presenilin 2 (PS1/2). We investigated the effect of the Swedish APP double mutation (APPsw) on oxidative stress-induced cell death mechanisms in PC12 cells. This mutation results in from three- to sixfold increased beta-amyloid (Abeta) production compared with wild-type APP (APPwt). Because APPsw cells secrete low Abeta levels similar to the situation in FAD brains, our cell model represents a very suitable approach to elucidate the AD-specific cell death pathways under more likely physiological conditions. We found that APPsw-bearing cells show decreased mitochondrial membrane potential after exposure to hydrogen peroxide. In addition, activity of the executor caspase 3 after treatment with hydrogen peroxide was elevated in APPsw cells, which seems to be the result of an enhanced activation of both intrinsic and extrinsic apoptosis pathways. Our findings provide evidence that the massive neurodegeneration in early age of FAD patients could be a consequence of an increased vulnerability of neurons by mitochondrial abnormalities resulting in activation of different apoptotic pathways as a consequence to elevated oxidative stress levels. Finally, we propose a hypothetical sequence of the pathogenic steps linking sporadic AD, FAD, Abeta production, mitochondrial dysfunction with caspase pathway, and neuronal loss