Universitätspublikationen
Refine
Year of publication
Document Type
- Article (12911)
- Part of Periodical (3427)
- Doctoral Thesis (3156)
- Contribution to a Periodical (2075)
- Book (2051)
- Working Paper (1869)
- Preprint (1290)
- Review (1047)
- Report (910)
- Conference Proceeding (659)
Language
- English (16181)
- German (13530)
- Portuguese (231)
- Spanish (123)
- Italian (65)
- French (64)
- Multiple languages (57)
- Turkish (12)
- Ukrainian (10)
- slo (7)
Keywords
- Deutschland (132)
- COVID-19 (93)
- Financial Institutions (90)
- inflammation (90)
- ECB (67)
- Capital Markets Union (64)
- SARS-CoV-2 (63)
- Financial Markets (61)
- Adorno (58)
- Banking Union (50)
Institute
- Medizin (6214)
- Präsidium (4979)
- Physik (3053)
- Wirtschaftswissenschaften (2242)
- Gesellschaftswissenschaften (2009)
- Biowissenschaften (1666)
- Frankfurt Institute for Advanced Studies (FIAS) (1452)
- Sustainable Architecture for Finance in Europe (SAFE) (1369)
- Biochemie und Chemie (1359)
- Informatik (1350)
Introduction: This study reports about antenatal characteristics of Roma minority population. The study was designed to investigate data about health behaviours known to be associated with reproductive outcomes of Roma women that have very good living conditions and relatively high resource availability.
Methods: A retrospective study included 204 Roma and 408 non-Roma hospitalised singleton births that occurred in the Maternity Ward of the General Hospital Virovitica in the period from 1991 to 2010. Data about women’s age, marital status, smoking, reproductive health (abortions, delivery), antenatal care, perinatal complications and gestational age were taken from hospital records and analysed.
Results: Roma women were averagely more than three years younger than non-Roma women, only 10.8% were married. Smoking was more frequent. The average number of births of Roma and non-Roma women was similar, averagely two children per woman. The rate of induced abortions in the Roma women was higher, while the frequency of spontaneous abortions was equal. Inadequate antenatal care of Roma women was associated with two times higher incidence of perinatal complications. A higher frequency of deliveries at home without professional assistance in Roma pregnancy resulted in lower perinatal outcomes. It was confirmed that Roma mothers give birth earlier (38+6 vs. 39+4 weeks) and have a higher incidence of premature births (9.3% vs. 2.2%).
Conclusions: In the comparison of antenatal parameters between the two researched groups, poorer prenatal outcomes in the Roma population were found, despite full integration and considerable improvement in living standards of this ethnic Roma population.
Standard biorelevant media reflect the average gastrointestinal (GI) physiology in healthy volunteers. The use of biorelevant media in in vitro experiments has become an important strategy to predict drug behaviour in vivo and is often combined with in silico tools in order to simulate drug plasma profiles over time. In addition to the healthy population, the effects of disease state or co-administration of other drugs on plasma profiles must be considered to assure drug efficacy and safety. Thus, there is a need for a more accurate representation of the human GI physiology when it is altered by disease or co-administered drugs in in vitro dissolution experiments.
This thesis focused on the development of biorelevant media and dissolution tests reflecting GI physiology in circumstances where the gastric pH is elevated. Diseases linked to an elevated gastric pH are hypochlorhydria and achlorhydria, but these days treatment with acid-reducing agents (ARAs) is the single greatest cause of elevation in gastric pH. pH-dependent drug-drug interactions (DDIs) with ARAs are frequent, as the ARAs are used in a number of diseases using a variety of drugs. As the drugs currently on the market are often poorly soluble and ionisable, their dissolution is highly dependent on the pH of the GI tract, especially the gastric pH.
The thesis research consisted of several steps. In the first step, physiological changes in the human GI tract during the therapy with ARAs were identified. Parameters of the standard biorelevant gastric medium FaSSGF were adjusted to the identified changes to reflect the impact of ARA co-administration on the gastric physiology. The media aim to assess the potential extent of the ARA impact on gastric physiology by introducing biorelevant media pairs, ARA pH 4 and pH 6 media, of which one reflects a lesser, and the other a stronger impact of ARAs.
In the second step these ARA media were implemented in in vitro dissolution set-ups.
The dissolution of poorly soluble ionisable drugs was assessed using one-stage, two-stage and transfer model set-ups, as well as using a more evolved in vitro system TIM-1. Comparison of results from dissolution set-ups using the standard, low pH, gastric biorelevant medium FaSSGF (pH 1.6 or 2), and the same set-ups using ARA pH 4 and pH 6 media, shows a decrease in dissolution rate and extent for weakly basic compounds PSWB 001 and dipyridamole, and an increase in rate and extent of dissolution for the weakly acidic compound raltegravir potassium, when the gastric pH is elevated. Due to different physicochemical properties, the extent of the impact of physiological changes during ARA therapy (when either ARA pH 4 or pH 6 medium is selected) on dissolution varied among the model drugs. Thus, the bracketing approach, which considers a range of the possible ARA co-administration impact on drug dissolution, was confirmed to be best practice in assessing the impact of ARAs.
In the third step, dissolution data from in vitro experiments with ARA media was implemented into in silico models. The predictions using various in silico model approaches in Simcyp™ Simulator (minimal and full PBPK model, dissolution input using DRM and DLM) successfully bracketed in vivo data on drug administration during ARA therapy and correctly predicted an overall decrease in plasma concentration for the two model weakly basic compounds and an increase in plasma concertation for the model weakly acidic compound.
In all assessed scenarios, the ARA methods proved to be an essential part of evaluating and predicting the impact of ARAs on drug pharmacokinetics, and appropriately predicted the extent of a possible impact of ARAs on the drug plasma profiles. Thus, the ARA biorelevant media and dissolution tests were demonstrated to be valuable tools reflecting administration of drugs when the gastric pH is elevated and able to predict the impact of ARA therapy on drug administration.
The ability to evaluate the impact of human (patho) physioloy on drug behaviour in the gastrointestinal tract is of great importance, as the GI conditions play a significant role in drug release and absorption. Thus, there is great interest on the part of the pharmaceutical industry and regulatory agencies to develop best practices in this field, especially for pH-dependent DDIs. The media and dissolution tests developed in this thesis are biorelevant methods appropriate for evaluation of the impact of elevated gastric pH on drug efficacy and safety. Such methods, used as a risk assessment tool, in connection with evaluation of the efficacy window and potential toxicity, may help to increase confidence about decisions as to whether a pH-effect will occur and whether it is relevant or not, prior to conducting clinical studies. They may also enable changes in inclusion/exclusion criteria during recruiting for large-scale efficacy trials. In fact, the biopharmaceutic approach to drug development is becoming standard practice on a number of fronts, including metabolic DDIs, renal and hepatic insufficiency, powering decision-making process and possibly even waiving certain types of clinical studies.
...
A recent report showed PINK1 transcript levels to be up- or down-regulated by the gain or loss of Ataxin-2 function, respectively, in human blood, in a human neural cell line and in mouse tissues. These observations may have profound implications for the regulation of cell growth and may be medically exploited for the treatment of cancer and neural atrophy...
Ataxin-2 (human gene symbol ATXN2) acts during stress responses, modulating mRNA translation and nutrient metabolism. Ataxin-2 knockout mice exhibit progressive obesity, dyslipidemia, and insulin resistance. Conversely, the progressive ATXN2 gain of function due to the fact of polyglutamine (polyQ) expansions leads to a dominantly inherited neurodegenerative process named spinocerebellar ataxia type 2 (SCA2) with early adipose tissue loss and late muscle atrophy. We tried to understand lipid dysregulation in a SCA2 patient brain and in an authentic mouse model. Thin layer chromatography of a patient cerebellum was compared to the lipid metabolome of Atxn2-CAG100-Knockin (KIN) mouse spinocerebellar tissue. The human pathology caused deficits of sulfatide, galactosylceramide, cholesterol, C22/24-sphingomyelin, and gangliosides GM1a/GD1b despite quite normal levels of C18-sphingomyelin. Cerebellum and spinal cord from the KIN mouse showed a consistent decrease of various ceramides with a significant elevation of sphingosine in the more severely affected spinal cord. Deficiency of C24/26-sphingomyelins contrasted with excess C18/20-sphingomyelin. Spinocerebellar expression profiling revealed consistent reductions of CERS protein isoforms, Sptlc2 and Smpd3, but upregulation of Cers2 mRNA, as prominent anomalies in the ceramide–sphingosine metabolism. Reduction of Asah2 mRNA correlated to deficient S1P levels. In addition, downregulations for the elongase Elovl1, Elovl4, Elovl5 mRNAs and ELOVL4 protein explain the deficit of very long-chain sphingomyelin. Reduced ASMase protein levels correlated to the accumulation of long-chain sphingomyelin. Overall, a deficit of myelin lipids was prominent in SCA2 nervous tissue at prefinal stage and not compensated by transcriptional adaptation of several metabolic enzymes. Myelination is controlled by mTORC1 signals; thus, our human and murine observations are in agreement with the known role of ATXN2 yeast, nematode, and mouse orthologs as mTORC1 inhibitors and autophagy promoters.
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative movement disorder caused by expansion of CAG repeats in the ATXN2 gene beyond 33 units, while healthy individuals carry 22-23 repeats. First symptoms of SCA2 include uncoordinated movement, ataxic gait and slowing of the saccadic eye movements in line with the early pronounced atrophy of cerebellum, spinal cord and brainstem. Cerebellar Purkinje cells and spinal cord motor neurons are the most affected cells from ATXN2 expansions. Later on, patients manifest distal amyotrophy, problems in breathing and swallowing, depression and cognitive decline caused by widespread degeneration throughout the brain. The striking loss of mass in the brain, due to severe myelin fat atrophy, is accompanied by a similar reduction in the peripheral fat stores. After the devastating progression of disease, the severity and duration of which depends on the CAG repeat size, genetic background and environmental factors, patients succumb to SCA2 mostly because of respiratory failure at the terminal stage. Larger repeat sizes lead to an earlier manifestation of the disease and a more rapid progression. Aside from SCA2, intermediate-length and short pathogenic CAG expansions in ATXN2 between 26-39 repeats significantly increase the risk of developing other neurodegenerative disorders, such as amyotrophic lateral sclerosis (ALS), fronto-temporal lobar dementia (FTLD) or Parkinson plus tauopathies like progressive supranuclear palsy (PSP) in various cohorts across the world.
Ataxin-2 (ATXN2) is a ubiquitously expressed cytosolic protein most famous for its involvement in neurodegenerative disease caused by the expanded poly-glutamine (polyQ) domain corresponding to a genomic (CAG)n tract. This N-terminal polyQ domain has no known function, other than increasing the aggregation propensity of mutant ATXN2 and facilitating interaction with other polyQ containing proteins, leading to their sequestration. The progressive accumulation of ATXN2 into cytosolic foci, and also that of its interaction partners over time, underlies the molecular pathomechanism. Next to polyQ domain, ATXN2 also contains a Like-Sm domain (Lsm), an Lsm-associated domain (LsmAD), multiple proline-rich domains (PRD) and a Poly(A)-Binding-Protein (PABP)-interacting motif (PAM2).
Through its Lsm/LsmAD domains, ATXN2 directly binds to a large number of transcripts, regulating their quality and translation rate. In a similar fashion, through its direct interaction with PABP via PAM2 motif, ATXN2 indirectly modifies the fate of even larger number of transcripts and global translation. Several PRDs scattered across the protein help ATXN2 associate with growth factor receptors and other endocytosis factors, modulating nutrient uptake and downstream signaling.
ATXN2 is a stress response factor. Therefore, its involvement in nutrient uptake plays a crucial part in cell’s capability to overcome non-permissive conditions. Upon nutrient deprivation, oxidative stress, proteotoxicity, heat stress or Ca2+ imbalance, ATXN2 relocalizes into cytosolic ribonucleoprotein particles known as stress granules (SGs), together with PABP, several eukaryotic translation initiation factors, many other RNA-binding proteins (RBP) with their target transcripts and the small ribosomal subunit. Collectively, they modulate the stability of the trapped transcripts, favoring the maturation and translation of IRES-dependent stress response proteins instead, according to the specific need. Many RBPs interact either directly or in an RNA-dependent manner in the SGs, and due to the large number of ALS-causing mutations identified in them (such as TDP-43, FUS, TIA-1, hnRNPA2/B1), SGs became a hot topic in neuropathology. Acute SGs serve to halt translation and growth, and to spend energy only for survival until stress disappears. However, chronic SG assembly eventually activates apoptotis leading to cell death. While the polyQ expansions in ATXN2 enhance SG stability, reduce their dissociation rate after stress, and lead to aberrant post-translational modifications of other SG components like TDP-43, complete loss of ATXN2 delays SG formation and results in easily dissolvable foci.
Most of the stressors that induce SG formation eventually converge on energetic deficit. Therefore, it is logical that the ultimate task of SGs is to stop further growth when it cannot be afforded. In yeast, the molecular mechanism underlying this growth arrest was explained as sequestration of the master growth regulator complex, Target-of-Rapamycin Complex 1 (TORC1), into SGs in an ATXN2-dependent manner. The repressor effect of ATXN2 on mammalian TORC1 (mTORC1) and global protein translation had already been documented in earlier studies; complete loss of ATXN2 function in knock-out mouse (Atxn2-KO) resulted in mTORC1 hyperactivity and transcriptional upregulation of multiple ribosomal subunits indicating an increased need for these machines. ...
The interdependence of selective cues during development of regulatory T cells (Treg cells) in the thymus and their suppressive function remains incompletely understood. Here, we analyzed this interdependence by taking advantage of highly dynamic changes in expression of microRNA 181 family members miR-181a-1 and miR-181b-1 (miR-181a/b-1) during late T-cell development with very high levels of expression during thymocyte selection, followed by massive down-regulation in the periphery. Loss of miR-181a/b-1 resulted in inefficient de novo generation of Treg cells in the thymus but simultaneously permitted homeostatic expansion in the periphery in the absence of competition. Modulation of T-cell receptor (TCR) signal strength in vivo indicated that miR-181a/b-1 controlled Treg-cell formation via establishing adequate signaling thresholds. Unexpectedly, miR-181a/b-1–deficient Treg cells displayed elevated suppressive capacity in vivo, in line with elevated levels of cytotoxic T-lymphocyte–associated 4 (CTLA-4) protein, but not mRNA, in thymic and peripheral Treg cells. Therefore, we propose that intrathymic miR-181a/b-1 controls development of Treg cells and imposes a developmental legacy on their peripheral function.
B-cell development and function depend on stage-specific signaling through the B-cell antigen receptor (BCR). Signaling and intracellular trafficking of the BCR are connected, but the molecular mechanisms of this link are incompletely understood. Here, we investigated the role of the endosomal adaptor protein and member of the LAMTOR/Ragulator complex LAMTOR2 (p14) in B-cell development. Efficient conditional deletion of LAMTOR2 at the pre-B1 stage using mb1-Cre mice resulted in complete developmental arrest. Deletion of LAMTOR2 using Cd19-Cre mice permitted analysis of residual B cells at later developmental stages, revealing that LAMTOR2 was critical for the generation and activation of mature B lymphocytes. Loss of LAMTOR2 resulted in aberrant BCR signaling due to delayed receptor internalization and endosomal trafficking. In conclusion, we identify LAMTOR2 as critical regulator of BCR trafficking and signaling that is essential for early B-cell development in mice.
Resistant microbes are a growing concern. It was estimated that about 33,000 of people die because of the infections caused by multidrug resistant bacteria each year in Europe (ECDC, 2018, https://www.ecdc.europa.eu/). Bacteria can acquire resistance against toxic compounds via different mechanisms and intrinsic active efflux is one of the first mechanisms deployed by bacterial cells. The membrane-localized efflux pumps catalysing this reaction, extract toxic compounds from the interior of the cell and transport these to the outside, thereby maintaining sub-lethal toxin levels in the cytoplasm, periplasm and membranes. Gram-negative three-component efflux pumps, analysed in this study, are composed of an inner membrane protein, a member of the Resistance-Nodulation cell Division (RND) superfamily, an Outer Membrane Factor (OMF) protein and a Membrane Fusion Protein (MFP) that connects the two afore mentioned components into an active efflux pump. The pumps described in this work, AcrAB-TolC and EmrAB-TolC, are drug efflux pumps belonging to the RND and MFS superfamilies, respectively, while CusCBA is an efflux pump that belongs to the RND heavy metal efflux family. Another efflux pump that was used as a model for the design of an in vitro assay for the silver ion transport studies, CopA, belongs to the P-type ATPase superfamily. All pumps analysed in this study are part of the resistance system of Escherichia coli, which is a highly clinically relevant pathogen.
In order to examine the AcrAB-TolC, CopA and CusA efflux pumps, the individual components were separately produced in E. coli, purified to monodispersity and reconstituted in large unilamellar vesicles, LUVs. Means for the optimized production and adequate conditions for efficient reconstitution were presented in this study. The activity of AcrB in LUVs was detected using fluorescence quenching of the dye 8-hydroxy-1,3,6 pyrenetrisulfonate (pyranine), which is incorporated inside the proteoliposomes and is sensitive to the pH changes in its surrounding. The inactive AcrB variant with a substitution in the proton relay network, D407N, showed no activity in proteoliposomes, which correlates with the measurements done in empty liposomes. When AcrA was co-reconstituted with AcrB D407N proteoliposomes it did not restore protein activity. To test the assembly of the AcrAB-TolC pump out of its single components, an in vitro assay was established where the complex assembly was tested with AcrAB- and TolC-containing liposomes. These experiments showed putative AcrAB-TolC formation in the presence or absence of a pump substrate, taurocholate, as well as in the presence of the pump inhibitor, MBX3132. The assembly appeared stable over time and results were invariant in the presence or absence of a pH gradient across the AcrAB-containing membrane.
After determination of the ATPase activity of the P-type ATPase, CopA, in detergent micelles, the protein was reconstituted in LUVs. Quenching of the Ag+-sensitive dye Phen Green SK (PGSK), present on the inside of the CopA-containing proteoliposomes, was observed in presence of ATP and Ag+. Under the same conditions, but in absence of Ag+-ions, quenching was reduced by 80 % after 300 seconds. No PGSK-quenching was observed in control liposomes in the presence of ATP and Ag+. The additional presence of sodium azide led to minimal reduction of the PGSK-quenching as expected since sodium azide is not an inhibitor of P-type ATPases, but the quenching rate was similar to that of the same experimental condition with control liposomes.
The RND superfamily member CusA, as part of the tripartite CusCBA efflux pump, has been proposed to sequester Ag+ or Cu+ from either the cytoplasmic or periplasmic side of the inner membrane. The periplasmic transport of silver ions was implied from an in vitro assay where the quenching of a pH sensitive dye, 9-amino-6-chloro-2-methoxyacridine (ACMA), indicates acidification of the lumen of the proteoliposomes containing CusA when an inwardly directed pH was imposed. The same experiment with the CusA D405N variant, which was previously reported to be an inactive variant, also led to ACMA quenching, although at a slightly lower rate. Under application of an inwardly directed pH and a (negative inside), CusA-containing proteoliposomes showed a strong quenching of the incorporated PGSK dye, suggesting strong Ag+ influx.
The Major Facilitator Superfamily-(MFS-) type EmrAB-TolC pump has an analogous structural setup as the RND-type AcrAB-TolC pump. To examine the efflux of one of its substrates, carbonyl - cyanide m-chlorophenylhydrazone (CCCP), a plate-based susceptibility assay was used. The presence of the EmrAB-TolC pump confers lower susceptibility levels towards CCCP in E. coli, compared to cells not expressing the pump or cells expressing only the MFS component, indicating that EmrAB-TolC extrudes CCCP.
The work done in this study opens up a path towards investigation of drug and metal resistance in vitro. The methodologies to obtain proteoliposomal samples of multicomponent efflux pumps and subsequent measurements of drug/metal ion and H+ fluxes, as well as the determination of pump assembly are crucial for the future research on pump catalysis and transport kinetics. The in vivo drug-plate assays done in this work provide initial insights for future investigations of the drug susceptibility of E. coli expressing the MFS-type tripartite efflux pumps.
Ubiquitin ligases and beyond
(2012)
First paragraph (this article has no abstract): In a review published in 2004 [1] and that still repays reading today, Cecile Pickart traced the evolution of research on ubiquitination from its origins in the proteasomal degradation of proteins through the revelation that it has a central role in cell cycle regulation and the recognition of regulatory roles for ubiquitin in intracellular membrane transport, cell signalling, transcription, translation, and DNA repair.