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Acetylcholine (ACh) mediates transmission at vertebrate neuromuscular junctions and many other synapses. The postsynaptic ACh receptors at neuromuscular junctions are of the nicotinic subtype (nAChRs). They are among the best studied receptor channels and often serve as models or receptor prototypes. Despite a wealth of information on muscle type nAChRs so far little is known about species specific functional differences. In this work, mouse and human adult muscle type nAChRs are investigated.
Cell attached recordings in the HEK293T heterologous expression system provided evidence that the ACh affinity of recombinant mouse and human adult muscle type nAChRs are different. To clarify this, I compared these receptors in outside-out patches employing a system for fast agonist application. Thus, the individual membrane patches with receptors can be exposed to various ligand concentrations. In response to 10 and 30 µM ACh normalized peak currents (î) were significantly larger and current rise-time (tr) shorter in human than in mouse receptors. Analyzing dose-response curves of î and tr and fitting them with a two-step equivalent binding-site kinetic mechanism revealed a two-fold higher ACh association rate constant in human compared to mouse receptors. Furthermore, human nAChRs were blocked faster in outside-out patches by superfusion of 300 nM α-Bungarotoxin (α-Bgtx) than mouse nAChRs. Finally, human nAChRs in outside-out patches showed higher affinity at 3 µM ACh than chimeric receptors consisting of mouse α- and human β-, γ- and ε-subunits. The higher affinity of human than mouse receptors for ACh and α-Bgtx is thus at least in part due to sequence difference in their α-subunits.
In recent years, numerous renewable energy cities were established worldwide, piloting different pathways to transition to clean energy. With the ability to address local needs more precisely in their unique geographic, social and economic contexts, cities play a vital role in implementing overall climate mitigation goals on the local level. In China, many renewable energy cities have emerged as well. However, official documents suggest that Chinese government authorities establish such renewable energy cities strategically, which leads to the assumption that the impulse to become renewable is different from other countries, where bottom-up initiatives are more common. Hence, this thesis explores answer to the question why and how the Chinese government promotes the energy transition of Chinese cities and regions. To explore the dynamics of local energy transition projects, this thesis adopts two frameworks from the field of sustainability transitions, the multi-level perspective and strategic niche management, and applies them to seven European and two Chinese case studies. The European sample includes the cities Graz, Güssing, Freiburg, and Helsinki as well as the communities Feldheim, Jühnde and Murau. The Chinese sample consists of the bottom-up initiative Shaanxi Sunflower Project and the demonstration project Tongli New Energy Town. A comparative analysis evaluates in how far the cases correspond to the multi-level perspective or strategic niche management. The comparison of the case studies reveals that the development of renewable energy cities in China goes beyond a top-down vs. bottom-up logic. In the Chinese context, strategic niche management should be understood as experimentation under hierarchy, which serves at pretesting different approaches before rolling them out nationwide. In addition, the analysis shows that both the multi-level perspective and strategic niche management have their advantages and disadvantages for niche development. Niches following the logic of the multi-level perspective may result in higher stakeholder acceptance, whereas strategic niche management can in turn accelerate niche development. However, since natural niche development cannot be steered intentionally, decision-makers who intend to induce local renewable energy projects have no other option but to resort to strategic niche management. To increase stakeholder acceptance and thus to improve the project outcome, decision-makers are advised to accommodate sufficient room for stakeholder participation in the project design.
A 1,8-naphthyridine diphosphine (NDP) reacts with boron-containing Lewis acids to generate complexes featuring a number of different naphthyridine bonding modes. When exposed to diborane B\(_{2}\)Br\(_{4}\), NDP underwent self-deprotonation to afford [NDP-B\(_{2}\)Br\(_{3}\)]Br, an unsymmetrical diborane comprised of four fused rings. The reaction of two equivalents of monoborane BBr\(_{3}\) and NDP in a non-polar solvent provided the simple phosphine-borane adduct [NDP(BBr\(_{3}\))\(_{2}\)], which then underwent intramolecular halide abstraction to furnish the salt [NDP-BBr\(_{2}\)][BBr\(_{4}\)], featuring a different coordination mode from that of [NDP-B\(_{2}\)Br\(_{3}\)]Br. Direct deprotonation of NDP by KHMDS or PhCH2K generates mono- and dipotassium reagents, respectively. The monopotassium reagent reacts with one or half an equivalent of B\(_{2}\)(NMe\(_{2}\))\(_{2}\)Cl\(_{2}\) to afford NDP-based diboranes with three or four amino substituents.
Background
A phase I/II study and subsequent phase III study (MPACT) reported significant correlations between CA19-9 decreases and prolonged overall survival (OS) with nab-paclitaxel plus gemcitabine (nab-P + Gem) treatment for metastatic pancreatic cancer (MPC). CA19-9 changes at week 8 and potential associations with efficacy were investigated as part of an exploratory analysis in the MPACT trial.
Patients and methods
Untreated patients with MPC (N = 861) received nab-P + Gem or Gem alone. CA19-9 was evaluated at baseline and every 8 weeks.
Results
Patients with baseline and week-8 CA19-9 measurements were analyzed (nab-P + Gem: 252; Gem: 202). In an analysis pooling the treatments, patients with any CA19-9 decline (80%) versus those without (20%) had improved OS (median 11.1 versus 8.0 months; P = 0.005). In the nab-P + Gem arm, patients with (n = 206) versus without (n = 46) any CA19-9 decrease at week 8 had a confirmed overall response rate (ORR) of 40% versus 13%, and a median OS of 13.2 versus 8.3 months (P = 0.001), respectively. In the Gem-alone arm, patients with (n = 159) versus without (n = 43) CA19-9 decrease at week 8 had a confirmed ORR of 15% versus 5%, and a median OS of 9.4 versus 7.1 months (P = 0.404), respectively. In the nab-P + Gem and Gem-alone arms, by week 8, 16% (40/252) and 6% (13/202) of patients, respectively, had an unconfirmed radiologic response (median OS 13.7 and 14.7 months, respectively), and 79% and 84% of patients, respectively, had stable disease (SD) (median OS 11.1 and 9 months, respectively). Patients with SD and any CA19-9 decrease (158/199 and 133/170) had a median OS of 13.2 and 9.4 months, respectively.
Conclusion
This analysis demonstrated that, in patients with MPC, any CA19-9 decrease at week 8 can be an early marker for chemotherapy efficacy, including in those patients with SD. CA19-9 decrease identified more patients with survival benefit than radiologic response by week 8.
In contrast to the plasma membrane, the vacuole membrane has not yet been associated with electrical excitation of plants. Here, we show that mesophyll vacuoles from Arabidopsis sense and control the membrane potential essentially via the K\(^+\)-permeable TPC1 and TPK channels. Electrical stimuli elicit transient depolarization of the vacuole membrane that can last for seconds. Electrical excitability is suppressed by increased vacuolar Ca\(^{2+}\) levels. In comparison to wild type, vacuoles from the fou2 mutant, harboring TPC1 channels insensitive to luminal Ca\(^{2+}\), can be excited fully by even weak electrical stimuli. The TPC1-loss-of-function mutant tpc1-2 does not respond to electrical stimulation at all, and the loss of TPK1/TPK3-mediated K\(^{+}\) transport affects the duration of TPC1-dependent membrane depolarization. In combination with mathematical modeling, these results show that the vacuolar K\(^+\)-conducting TPC1 and TPK1/TPK3 channels act in concert to provide for Ca\(^{2+}\)- and voltage-induced electrical excitability to the central organelle of plant cells.
In invertebrates, small interfering RNAs are at the vanguard of cell-autonomous antiviral immunity. In contrast, antiviral mechanisms initiated by interferon (IFN) signaling predominate in mammals. Whilst mammalian IFN-induced miRNA are known to inhibit specific viruses, it is not known whether host-directed microRNAs, downstream of IFN-signaling, have a role in mediating broad antiviral resistance. By performing an integrative, systematic, global analysis of RNA turnover utilizing 4-thiouridine labeling of newly transcribed RNA and pri/pre-miRNA in IFN-activated macrophages, we identify a new post-transcriptional viral defense mechanism mediated by miR-342-5p. On the basis of ChIP and site-directed promoter mutagenesis experiments, we find the synthesis of miR-342-5p is coupled to the antiviral IFN response via the IFN-induced transcription factor, IRF1. Strikingly, we find miR-342-5p targets mevalonate-sterol biosynthesis using a multihit mechanism suppressing the pathway at different functional levels: transcriptionally via SREBF2, post-transcriptionally via miR-33, and enzymatically via IDI1 and SC4MOL. Mass spectrometry-based lipidomics and enzymatic assays demonstrate the targeting mechanisms reduce intermediate sterol pathway metabolites and total cholesterol in macrophages. These results reveal a previously unrecognized mechanism by which IFN regulates the sterol pathway. The sterol pathway is known to be an integral part of the macrophage IFN antiviral response, and we show that miR-342-5p exerts broad antiviral effects against multiple, unrelated pathogenic viruses such Cytomegalovirus and Influenza A (H1N1). Metabolic rescue experiments confirm the specificity of these effects and demonstrate that unrelated viruses have differential mevalonate and sterol pathway requirements for their replication. This study, therefore, advances the general concept of broad antiviral defense through multihit targeting of a single host pathway.
Brushite cements have been clinically used for irregular bone defect filling applications, and various strategies have been previously reported to modify and improve their physicochemical properties such as strength and injectability. However, strategies to address other limitations of brushite cements such as low radiopacity or acidity without negatively impacting mechanical strength have not yet been reported. In this study, we report the effect of substituting the beta-tricalcium phosphate reactant in brushite cement with baghdadite (Ca\(_3\)ZrSi\(_2\)O\(_9\)), a bioactive zirconium-doped calcium silicate ceramic, at various concentrations (0, 5, 10, 20, 30, 50, and 100 wt%) on the properties of the final brushite cement product. X-ray diffraction profiles indicate the dissolution of baghdadite during the cement reaction, without affecting the crystal structure of the precipitated brushite. EDX analysis shows that calcium is homogeneously distributed within the cement matrix, while zirconium and silicon form cluster-like aggregates with sizes ranging from few microns to more than 50 µm. X-ray images and µ-CT analysis indicate enhanced radiopacity with increased incorporation of baghdadite into brushite cement, with nearly a doubling of the aluminium equivalent thickness at 50 wt% baghdadite substitution. At the same time, compressive strength of brushite cement increased from 12.9 ± 3.1 MPa to 21.1 ± 4.1 MPa with 10 wt% baghdadite substitution. Culture medium conditioned with powdered brushite cement approached closer to physiological pH values when the cement is incorporated with increasing amounts of baghdadite (pH = 6.47 for pure brushite, pH = 7.02 for brushite with 20 wt% baghdadite substitution). Baghdadite substitution also influenced the ionic content in the culture medium, and subsequently affected the proliferative activity of primary human osteoblasts in vitro. This study indicates that baghdadite is a beneficial additive to enhance the radiopacity, mechanical performance and cytocompatibility of brushite cement
A one-pot synthesis of a CAAC-stabilized, unsymmetrical, cyclic diborene was achieved via consecutive two-electron reduction steps from an adduct of CAAC and B\(_2\)Br\(_4\)(SMe\(_2\))\(_2\). Theoretical studies revealed that this diborene has a considerably smaller HOMO–LUMO gap than those of reported NHC- and phosphine-supported diborenes. Complexation of the diborene with [AuCl(PCy\(_3\))] afforded two diborene–Au\(^I\) π complexes, while reaction with DurBH\(_2\), P\(_4\) and a terminal acetylene led to the cleavage of B−H, P−P, and C−C π bonds, respectively. Thermal rearrangement of the diborene gave an electron-rich cyclic alkylideneborane, which readily coordinated to Ag\(^I\) via its B=C double bond.
Unisexual reproduction, which generates clonal offspring, is an alternative strategy to sexual breeding and occurs even in vertebrates. A wide range of non-sexual reproductive modes have been described, and one of the least understood questions is how such pathways emerged and how they mechanistically proceed. The Amazon molly, Poecilia formosa, needs sperm from males of related species to trigger the parthenogenetic development of diploid eggs. However, the mechanism, of how the unreduced female gametes are produced, remains unclear. Cytological analyses revealed that the chromosomes of primary oocytes initiate pachytene but do not proceed to bivalent formation and meiotic crossovers. Comparing ovary transcriptomes of P. formosa and its sexual parental species revealed expression levels of meiosis-specific genes deviating from P. mexicana but not from P. latipinna. Furthermore, several meiosis genes show biased expression towards one of the two alleles from the parental genomes. We infer from our data that in the Amazon molly diploid oocytes are generated by apomixis due to a failure in the synapsis of homologous chromosomes. The fact that this failure is not reflected in the differential expression of known meiosis genes suggests the underlying molecular mechanism may be dysregulation on the protein level or misexpression of a so far unknown meiosis gene, and/or hybrid dysgenesis because of compromised interaction of proteins from diverged genomes.