Discussion paper: implications for the further development of the successfully in emergency medicine implemented AUD2IT-algorithm.

The AUD2IT-algorithm is a tool to structure the data, which is collected during an emergency treatment. The goal is on the one hand to structure the documentation of the data and on the other hand to give a standardised data structure for the report during handover of an emergency patient. AUD2IT-algorithm was developed to provide residents a documentation aid, which helps to structure the medical reports without getting lost in unimportant details or forgetting important information. The sequence of anamnesis, clinical examination, considering a differential diagnosis, technical diagnostics, interpretation and therapy is rather an academic classification than a description of the real workflow. In a real setting, most of these steps take place simultaneously. Therefore, the application of the AUD2IT-algorithm should also be carried out according to the real processes. A big advantage of the AUD2IT-algorithm is that it can be used as a structure for the entire treatment process and also is entirely usable as a handover protocol within this process to make sure, that the existing state of knowledge is ensured at each point of a team-timeout. PR-E-(AUD2IT)-algorithm makes it possible to document a treatment process that, in principle, does not have to be limited to the field of emergency medicine. Also, in the outpatient treatment the PR-E-(AUD2IT)-algorithm could be used and further developed. One example could be the preparation and allocation of needed resources at the general practitioner. The algorithm is a standardised tool that can be used by healthcare professionals of any level of training. It gives the user a sense of security in their daily work.

Human CRB1 and CRB2 form homo- and heteromeric protein complexes in the retina.

Crumbs homolog 1 (CRB1) is one of the key genes linked to retinitis pigmentosa and Leber congenital amaurosis, which are characterized by a high clinical heterogeneity. The Crumbs family member CRB2 has a similar protein structure to CRB1, and in zebrafish, Crb2 has been shown to interact through the extracellular domain. Here, we show that CRB1 and CRB2 co-localize in the human retina and human iPSC-derived retinal organoids. In retina-specific pull-downs, CRB1 was enriched in CRB2 samples, supporting a CRB1-CRB2 interaction. Furthermore, novel interactors of the crumbs complex were identified, representing a retina-derived protein interaction network. Using co-immunoprecipitation, we further demonstrate that human canonical CRB1 interacts with CRB1 and CRB2, but not with CRB3, which lacks an extracellular domain. Next, we explored how missense mutations in the extracellular domain affect CRB1-CRB2 interactions. We observed no or a mild loss of CRB1-CRB2 interaction, when interrogating various CRB1 or CRB2 missense mutants in vitro. Taken together, our results show a stable interaction of human canonical CRB2 and CRB1 in the retina.

[TeleCOVID Hessen: implications for the development of new indication areas]. / TeleCOVID Hessen: Implikationen für die Erschließung neuer Indikationsgebiete.

BACKGROUND: During the SARS-CoV­2 pandemic, the TeleCOVID application was developed in Hessen to connect the intensive care units via telemedicine. After successful implementation, the application should be extended to other indication areas in intensive care medicine. OBJECTIVES: The purpose of this study was to evaluate other indications for which the application can be used and which technical requirements are associated with this. MATERIALS AND METHODS: To answer these questions, guideline-based expert interviews were conducted, which were evaluated using a qualitative content analysis. RESULTS: The survey showed that TeleCOVID can be extended to other indication areas in intensive care. Numerous technical requirements were formulated that should be specifically considered when the application is further developed. CONCLUSIONS: The telemedical networking of intensive care units generates added value for the actors involved. However, it is important that the data is collected in the best possible standardized and structured way. The communication process should be automated wherever possible to minimise the workload for the participating persons.

Interactome Analysis Reveals a Link of the Novel ALMS1-CEP70 Complex to Centrosomal Clusters.

Alström syndrome (ALMS) is a very rare autosomal-recessive disorder, causing a broad range of clinical defects most notably retinal degeneration, type 2 diabetes, and truncal obesity. The ALMS1 gene encodes a complex and huge ∼0.5 MDa protein, which has hampered analysis in the past. The ALMS1 protein is localized to the centrioles and the basal body of cilia and is involved in signaling processes, for example, TGF-ß signaling. However, the exact molecular function of ALMS1 at the basal body remains elusive and controversial. We recently demonstrated that protein complex analysis utilizing endogenously tagged cells provides an excellent tool to investigate protein interactions of ciliary proteins. Here, CRISPR/Cas9-mediated endogenously tagged ALMS1 cells were used for affinity-based protein complex analysis. Centrosomal and microtubule-associated proteins were identified, which are potential regulators of ALMS1 function, such as the centrosomal protein 70 kDa (CEP70). Candidate proteins were further investigated in ALMS1-deficient hTERT-RPE1 cells. Loss of ALMS1 led to shortened cilia with no change in structural protein localization, for example, acetylated and É£-tubulin, Centrin-3, or the novel interactor CEP70. Conversely, reduction of CEP70 resulted in decreased ALMS1 at the ciliary basal body. Complex analysis of CEP70 revealed domain-specific ALMS1 interaction involving the TPR-containing C-terminal (TRP-CT) fragment of CEP70. In addition to ALMS1, several ciliary proteins, including CEP135, were found to specifically bind to the TPR-CT domain. Data are available via ProteomeXchange with the identifier PXD046401. Protein interactors identified in this study provide candidate lists that help to understand ALMS1 and CEP70 function in cilia-related protein modification, cell death, and disease-related mechanisms.

Paralog-specific TTC30 regulation of Sonic hedgehog signaling.

The intraflagellar transport (IFT) machinery is essential for cilia assembly, maintenance, and trans-localization of signaling proteins. The IFT machinery consists of two large multiprotein complexes, one of which is the IFT-B. TTC30A and TTC30B are integral components of this complex and were previously shown to have redundant functions in the context of IFT, preventing the disruption of IFT-B and, thus, having a severe ciliogenesis defect upon loss of one paralog. In this study, we re-analyzed the paralog-specific protein complexes and discovered a potential involvement of TTC30A or TTC30B in ciliary signaling. Specifically, we investigated a TTC30A-specific interaction with protein kinase A catalytic subunit α, a negative regulator of Sonic hedgehog (Shh) signaling. Defects in this ciliary signaling pathway are often correlated to synpolydactyly, which, intriguingly, is also linked to a rare TTC30 variant. For an in-depth analysis of this unique interaction and the influence on Shh, TTC30A or B single- and double-knockout hTERT-RPE1 were employed, as well as rescue cells harboring wildtype TTC30 or the corresponding mutation. We could show that mutant TTC30A inhibits the ciliary localization of Smoothened. This observed effect is independent of Patched1 but associated with a distinct phosphorylated PKA substrate accumulation upon treatment with forskolin. This rather prominent phenotype was attenuated in mutant TTC30B. Mass spectrometry analysis of wildtype versus mutated TTC30A or TTC30B uncovered differences in protein complex patterns and identified an impaired TTC30A-IFT57 interaction as the possible link leading to synpolydactyly. We could observe no impact on cilia assembly, leading to the hypothesis that a slight decrease in IFT-B binding can be compensated, but mild phenotypes, like synpolydactyly, can be induced by subtle signaling changes. Our systematic approach revealed the paralog-specific influence of TTC30A KO and mutated TTC30A on the activity of PRKACA and the uptake of Smoothened into the cilium, resulting in a downregulation of Shh. This downregulation, combined with interactome alterations, suggests a potential mechanism of how mutant TTC30A is linked to synpolydactyly.

WDR31 displays functional redundancy with GTPase-activating proteins (GAPs) ELMOD and RP2 in regulating IFT complex and recruiting the BBSome to cilium.

The correct intraflagellar transport (IFT) assembly at the ciliary base and the IFT turnaround at the ciliary tip are key for the IFT to perform its function, but we still have poor understanding about how these processes are regulated. Here, we identify WDR31 as a new ciliary protein, and analysis from zebrafish and Caenorhabditis elegans reveals the role of WDR31 in regulating the cilia morphology. We find that loss of WDR-31 together with RP-2 and ELMD-1 (the sole ortholog ELMOD1-3) results in ciliary accumulations of IFT Complex B components and KIF17 kinesin, with fewer IFT/BBSome particles traveling along cilia in both anterograde and retrograde directions, suggesting that the IFT/BBSome entry into the cilia and exit from the cilia are impacted. Furthermore, anterograde IFT in the middle segment travels at increased speed in wdr-31;rpi-2;elmd-1 Remarkably, a non-ciliary protein leaks into the cilia of wdr-31;rpi-2;elmd-1, possibly because of IFT defects. This work reveals WDR31-RP-2-ELMD-1 as IFT and BBSome trafficking regulators.

[Evaluation of the "TeleCOVID Hesse" project after 1 year in operation]. / Evaluation des Projekts "TeleCOVID Hessen" nach einjährigem Betrieb.

BACKGROUND: The SARS-CoV­2 pandemic posed unexpected challenges for hospitals worldwide and in addition to the supply emergency, simultaneously caused a high pressure to innovate. Due to the high number of cases of COVID-19 patients requiring intensive care, structured networking of hospitals gained particular importance. The tele-ICU communication platform TeleCOVID was developed to improve the quality of intensive care both by enabling teleconsultations and by supporting patient transfers. OBJECTIVE: The present study aimed to survey user experiences with TeleCOVID. The study investigated the extent to which the app is used, the user experiences of the participating hospitals, and the resulting implications for the further development of the telemedicine application. MATERIAL AND METHODS: A user survey was conducted in May 2022 using an online questionnaire. The survey contained both closed and open questions with a free text field. It was sent via the Hessian Ministry of Social Affairs and Integration (HMSI). All 135 hospitals in Hesse were contacted by e­mail and invited to participate in the study. The results of the closed questions were analyzed using descriptive statistics, and the results of the open questions were clustered and thematically summarized using qualitative content analysis. RESULTS: The study showed that TeleCOVID was used primarily for transfer requests, followed by the need for a treatment consultation without a transfer request. Most often, ECMO treatment or treatment in a hospital of a higher care level was required. The content analysis showed that users particularly rated the possibility of a data protection-compliant and structured transfer of patient data as advantageous. It is also worth mentioning that in almost 25% of the cases a transfer of patients could be prevented by TeleCOVID. Disadvantages frequently mentioned by respondents were the lack of connection to the electronic hospital information system, the increased time required for the registration process, and the poor primary accessibility of contact persons. CONCLUSION: In a further development of the application the connection to the electronic hospital information system should be considered particularly urgent. In addition, the time expenditure should be reduced by a simplified login process. Due to interface barriers, an alternative data infrastructure would also be conceivable to create interoperability. The introduction of a web client could also increase usability. The main beneficiaries of hospital networking are physicians and patients in a context associated with a high workload and specific medical issues. Continuation and expansion of the app to intensive care medicine and beyond are therefore recommended. In further studies on the project, personal interviews with decision makers could be useful to conduct a more targeted needs analysis.

Fingerprints of magnetoinduced charge density waves in monolayer graphene beyond half filling.

A charge density wave is a condensate of fermions, whose charge density shows a long-range periodic modulation. Such charge density wave can be principally described as a macroscopic quantum state and is known to occur by various formation mechanisms. These are the lattice deforming Peierls transition, the directional, fermionic wave vector orientation prone Fermi surface nesting or the generic charge ordering, which in contrast is associated solely with the undirected effective Coulomb interaction between fermions. In two-dimensional Dirac/Weyl-like systems, the existence of charge density waves is only theoretically predicted within the ultralow energy regime at half filling. Taking graphene as host of two-dimensional fermions described by a Dirac/Weyl Hamiltonian, we tuned indirectly the effective mutual Coulomb interaction between fermions through adsorption of tetracyanoquinodimethane on top in the low coverage limit. We thereby achieved the development of a novel, low-dimensional dissipative charge density wave of Weyl-like fermions, even beyond half filling with additional magneto-induced localization and quantization. This charge density wave appears both, in the electron and the hole spectrum.

Measuring sustainable tourism with online platform data.

Sustainability in tourism is a topic of global relevance, finding multiple mentions in the United Nations Sustainable Development Goals. The complex task of balancing tourism's economic, environmental, and social effects requires detailed and up-to-date data. This paper investigates whether online platform data can be employed as an alternative data source in sustainable tourism statistics. Using a web-scraped dataset from a large online tourism platform, a sustainability label for accommodations can be predicted reasonably well with machine learning techniques. The algorithmic prediction of accommodations' sustainability using online data can provide a cost-effective and accurate measure that allows to track developments of tourism sustainability across the globe with high spatial and temporal granularity. Supplementary Information: The online version contains supplementary material available at 10.1140/epjds/s13688-022-00354-6.

TTC30A and TTC30B Redundancy Protects IFT Complex B Integrity and Its Pivotal Role in Ciliogenesis.

Intraflagellar transport (IFT) is a microtubule-based system that supports the assembly and maintenance of cilia. The dysfunction of IFT leads to ciliopathies of variable severity. Two of the IFT-B components are the paralogue proteins TTC30A and TTC30B. To investigate whether these proteins constitute redundant functions, CRISPR/Cas9 was used to generate single TTC30A or B and double-knockout hTERT-RPE1 cells. Ciliogenesis assays showed the redundancy of both proteins while the polyglutamylation of cilia was affected in single knockouts. The localization of other IFT components was not affected by the depletion of a single paralogue. A loss of both proteins led to a severe ciliogenesis defect, resulting in no cilia formation, which was rescued by TTC30A or B. The redundancy can be explained by the highly similar interaction patterns of the paralogues; both equally interact with the IFT-B machinery. Our study demonstrates that a loss of one TTC30 paralogue can mostly be compensated by the other, thus preventing severe ciliary defects. However, cells assemble shorter cilia, which are potentially limited in their function, especially because of impaired polyglutamylation. A complete loss of both proteins leads to a deficit in IFT complex B integrity followed by disrupted IFT and subsequently no cilia formation.

The Na+-activated K+ channel Slack contributes to synaptic development and plasticity.

Human mutations of the Na+-activated K+ channel Slack (KCNT1) are associated with epilepsy and intellectual disability. Accordingly, Slack knockout mice (Slack-/-) exhibit cognitive flexibility deficits in distinct behavioral tasks. So far, however, the underlying causes as well as the role of Slack in hippocampus-dependent memory functions remain enigmatic. We now report that infant (P6-P14) Slack-/- lack both hippocampal LTD and LTP, likely due to impaired NMDA receptor (NMDAR) signaling. Postsynaptic GluN2B levels are reduced in infant Slack-/-, evidenced by lower amplitudes of NMDAR-meditated excitatory postsynaptic potentials. Low GluN2B affected NMDAR-mediated Ca2+-influx, rendering cultured hippocampal Slack-/-neurons highly insensitive to the GluN2B-specific inhibitor Ro 25-6981. Furthermore, dephosphorylation of the AMPA receptor (AMPAR) subunit GluA1 at S845, which is involved in AMPAR endocytosis during homeostatic and neuromodulator-regulated plasticity, is reduced after chemical LTD (cLTD) in infant Slack-/-. We additionally detect a lack of mGluR-induced LTD in infant Slack-/-, possibly caused by upregulation of the recycling endosome-associated small GTPase Rab4 which might accelerate AMPAR recycling from early endosomes. Interestingly, LTP and mGluR LTD, but not LTD and S845 dephosphorylation after cLTD are restored in adult Slack-/-. This together with normalized expression levels of GluN2B and Rab4 hints to developmental "restoration" of LTP expression despite Slack ablation, whereas in infant and adult brain, NMDAR-dependent LTD induction depends on this channel. Based on the present findings, NMDAR and vesicular transport might represent novel targets for the therapy of intellectual disability associated with Slack mutations. Consequently, careful modulation of hippocampal Slack activity should also improve learning abilities.

A general principle of dendritic constancy: A neuron's size- and shape-invariant excitability.

Reducing neuronal size results in less membrane and therefore lower input conductance. Smaller neurons are thus more excitable, as seen in their responses to somatic current injections. However, the impact of a neuron's size and shape on its voltage responses to dendritic synaptic activation is much less understood. Here we use analytical cable theory to predict voltage responses to distributed synaptic inputs in unbranched cables, showing that these are entirely independent of dendritic length. For a given synaptic density, neuronal responses depend only on the average dendritic diameter and intrinsic conductivity. This remains valid for a wide range of morphologies irrespective of their arborization complexity. Spiking models indicate that morphology-invariant numbers of spikes approximate the percentage of active synapses. In contrast to spike rate, spike times do depend on dendrite morphology. In summary, neuronal excitability in response to distributed synaptic inputs is largely unaffected by dendrite length or complexity.

Tissue- and isoform-specific protein complex analysis with natively processed bait proteins.

Protein-protein interaction analysis is an important tool to elucidate the function of proteins and protein complexes as well as their dynamic behavior. To date, the analysis of tissue- or even cell- or compartment-specific protein interactions is still relying on the availability of specific antibodies suited for immunoprecipitation. Here, we aimed at establishing a method that allows identification of protein interactions and complexes from intact tissues independent of specific, high affinity antibodies used for protein pull-down and isolation. Tagged bait proteins were expressed in human HEK293T cells and residual interactors removed by SDS. The resulting tag-fusion protein was then used as bait to pull proteins from tissue samples. Tissue-specific interactions were reproducibly identified from porcine retina as well as from retinal pigment epithelium using the ciliary protein lebercilin as bait. Further, murine heart-specific interactors of two gene products of the 3',5'-cyclic guanosine monophosphate (cGMP)-dependent protein kinase type 1 (cGK1) were investigated. Here, specific interactions were associated with the cGK1α and ß gene products, that differ only in their unique amino-terminal region comprising about 100 aa. As such, the new protocol provides a fast and reliable method for tissue-specific protein complex analysis which is independent of the availability or suitability of antibodies for immunoprecipitation. SIGNIFICANCE: Protein-protein interaction in the functional relevant tissue is still difficult due to the dependence on specific antibodies or bait production in bacteria or insect cells. Here, the tagged protein of interest is produced in a human cell line and bound proteins are gently removed using SDS. Because applying the suitable SDS concentration is a critical step, different SDS solutions were tested to demonstrate their influence on interactions and the clean-up process. The established protocol enabled a tissue-specific analysis of the ciliary proteins lebercilin and TMEM107 using pig eyes. In addition, two gene products of the 3',5'-cyclic guanosine monophosphate (cGMP)-dependent protein kinase type 1 showed distinct protein interactions in mouse heart tissue. With the easy, fast and cheap protocol presented here, deep insights in tissue-specific and functional relevant protein complex formation is possible.

[Video Consultation Hours in the Statutory Accident Insurance - Application Possibilities and Economic Evaluation]. / Videosprechstunden im berufsgenossenschaftlichen Heilverfahren ­ Anwendungsmöglichkeiten und ökonomische Evaluation.

OBJECTIVES: Video consultations are becoming more and more important for health care providers as they enable new treatment options. Since 2017 video consultations have been used by the public health insurance companies in Germany. However, similar options are lacking in the employer's liability insurance association (BG in Germany) health insurance system. The aim of this article is to present and discuss possible applications of video consultations in the latter system and to evaluate economic advantages. METHODS: Possible applications of video consultations are discussed in the context of feasibility, potential benefits and the existing scale of fees for physicians (in Germany UV-GOÄ). RESULTS: Video consultations can be used for follow-up evaluations as well as preparation for initial medical examinations especially in complex cases and for case conferences. Even though video consultations are not included in the reimbursement system, similar CPT codes (current procedural terminology) already do exist. CONCLUSIONS: Video consultations might help improve the quality and reduce the costs of the public health insurance system. Furthermore, since video consultations can be expected to become more important in the future, they should be included as a standard tool in the employer's liability insurance association insurance system and an adequate reimbursement system be established.

Cells in Silico - introducing a high-performance framework for large-scale tissue modeling.

BACKGROUND: Discoveries in cellular dynamics and tissue development constantly reshape our understanding of fundamental biological processes such as embryogenesis, wound-healing, and tumorigenesis. High-quality microscopy data and ever-improving understanding of single-cell effects rapidly accelerate new discoveries. Still, many computational models either describe few cells highly detailed or larger cell ensembles and tissues more coarsely. Here, we connect these two scales in a joint theoretical model. RESULTS: We developed a highly parallel version of the cellular Potts model that can be flexibly applied and provides an agent-based model driving cellular events. The model can be modular extended to a multi-model simulation on both scales. Based on the NAStJA framework, a scaling implementation running efficiently on high-performance computing systems was realized. We demonstrate independence of bias in our approach as well as excellent scaling behavior. CONCLUSIONS: Our model scales approximately linear beyond 10,000 cores and thus enables the simulation of large-scale three-dimensional tissues only confined by available computational resources. The strict modular design allows arbitrary models to be configured flexibly and enables applications in a wide range of research questions. Cells in Silico (CiS) can be easily molded to different model assumptions and help push computational scientists to expand their simulations to a new area in tissue simulations. As an example we highlight a 10003 voxel-sized cancerous tissue simulation at sub-cellular resolution.

Fractional flow reserve and frequency of PCI in patients with coronary artery disease.

BACKGROUND: Fractional flow reserve (FFR) guided percutaneous coronary intervention (PCI) has been validated in patients with stable coronary artery disease (CAD) but has not yet been verified under specific conditions such as heart failure or microvascular dysfunction. The aim of the present study was to examine the influence of specific patient comorbidities on FFR values and thus the frequency of PCI in patients with intermediate coronary stenosis. METHODS: A total of 652 patients with CAD and intermediate coronary stenosis who were assessed for FFR were included in this retrospective study. In a subgroup analysis, specific comorbidities such as heart failure with non-ST-segment-elevated acute coronary syndrome (NSTE-ACS), heart failure, diabetes mellitus, atrial fibrillation (AF), and left ventricular hypertrophy (LVH) were considered. RESULTS: In all lesions with an FFR ≤ 0.80 (n = 227/808, 28.1%), PCI was performed using drug-eluting stents. Pathological FFR values (FFR ≤ 0.80) before PCI were most frequently observed in the left anterior descending artery (LAD; n = 168/418, 39.9%) followed by the right coronary artery (RCA; n = 37/178, 20.7%) and the left circumflex artery (LCX; 22/223, 9.8%). The comorbidities NSTE-ACS (p = 0.28), heart failure with reduced ejection fraction (HFrEF; p = 0.63), heart failure with preserved ejection fraction (HFpEF; p = 0.3719), diabetes mellitus (p = 0.177), or LVH (p = 0.407) had no major impact on the occurrence of pathological FFR values; there was also no association between FFR and the occurrence of lesions in the different target vessels. CONCLUSION: The occurrence of pathological FFR values, most frequently documented in the LAD, was the same in patients with or without HFrEF, HFpEF, diabetes mellitus, AF, and LVH, demonstrating that these comorbidities did not influence FFR values and, thus, the indication for PCI.

Ultrafast Proton Transport between a Hydroxy Acid and a Nitrogen Base along Solvent Bridges Governed by the Hydroxide/Methoxide Transfer Mechanism.

Aqueous proton transport plays a key role in acid-base neutralization and energy transport through biological membranes and hydrogen fuel cells. Extensive experimental and theoretical studies have resulted in a highly detailed elucidation of one of the underlying microscopic mechanisms for aqueous excess proton transport, known as the von Grotthuss mechanism, involving different hydrated proton configurations with associated high fluxional structural dynamics. Hydroxide transport, with approximately 2-fold-lower bulk diffusion rates compared to those of excess protons, has received much less attention. We present femtosecond UV/IR pump-probe experiments and ab initio molecular dynamics simulations of different proton transport pathways of bifunctional photoacid 7-hydroxyquinoline (7HQ) in water/methanol mixtures. For 7HQ solvent-dependent photoacidity, free-energy-reactivity correlation behavior and quantum mechanics/molecular mechanics (QM/MM) trajectories point to a dominant OH-/CH3O- transport pathway for all water/methanol mixing ratios investigated. Our joint ultrafast infrared spectroscopic and ab initio molecular dynamics study provides conclusive evidence for the hydrolysis/methanolysis acid-base neutralization pathway, as formulated by Manfred Eigen half a century ago. Our findings on the distinctly different acid-base reactivities for aromatic hydroxyl and aromatic nitrogen functionalities suggest the usefulness of further exploration of these free-energy-reactivity correlations as a function of solvent polarity. Ultimately the determination of solvent-dependent acidities will contribute to a better understanding of proton-transport mechanisms at weakly polar surfaces and near polar or ionic regions in transmembrane proton pump proteins or hydrogen fuel cell materials.

Perturbation of the F19-L34 Contact in Amyloid ß (1-40) Fibrils Induces Only Local Structural Changes but Abolishes Cytotoxicity.

We explored structural details of fibrils formed by a mutated amyloid ß (Aß(1-40)) peptide carrying a Phe19 to Lys19 mutation, which was shown to completely abolish the toxicity of the molecule. Computer models suggest that the positively charged Lys19 side chain is expelled from the hydrophobic fibril interior upon fibrillation. This can be accommodated by either a 180° flip of the entire lower ß-strand (model M1) or local perturbations of the secondary structure in the direct vicinity of the mutated site (model M2). This is accompanied by the formation of a new salt bridge between Glu22 and Lys28 in model M1. Experimentally, a novel contact between Phe20 and Leu34 as well as the significant structural perturbation of residues 20-23 could be confirmed. However, the mutated fibrils do not show the formation of any salt bridges. This demonstrates that although morphologically very robust, local perturbations of the Aß(1-40) sequence lead to moderate structural alterations with tremendous impact on the physiological importance of these aggregates, which may suggest alternative strategies for the development of a remedy against Alzheimer's disease.

Improved Quantum Chemical NMR Chemical Shift Prediction of Metabolites in Aqueous Solution toward the Validation of Unknowns.

A quantum-chemistry based protocol, termed MOSS-DFT, is presented for the prediction of 13C and 1H NMR chemical shifts of a wide range of organic molecules in aqueous solution, including metabolites. Molecular motif-specific linear scaling parameters are reported for five different density functional theory (DFT) methods (B97-2/pcS-1, B97-2/pcS-2, B97-2/pcS-3, B3LYP/pcS-2, and BLYP/pcS-2), which were applied to a large set of 176 metabolite molecules. The chemical shift root-mean-square deviations (RMSD) for the best method, B97-2/pcS-3, are 1.93 and 0.154 ppm for 13C and 1H chemical shifts, respectively. Excellent results have been obtained for chemical shifts of methyl and aromatic 13C and 1H that are not directly bonded to a heteroatom (O, N, S, or P) with RMSD values of 1.15/0.079 and 1.31/0.118 ppm, respectively. This study not only demonstrates how NMR chemical shift in aqueous environment can be improved over the commonly used global linear scaling approach, but also allows for motif-specific error estimates, which are useful for an improved chemical shift-based verification of metabolite candidates of metabolomics samples containing unknown components.