Arrested dynamics in a model peptide hydrogel system

We report here on a peptide hydrogel system, which in contrast to most other such systems, is made up of relatively short fibrillar aggregates, discussing resemblance with colloidal rods

Self-assembly of the peptide A10K – Intermediate state in aggregate formation

We have studied the synthetic surfactant-like peptide A10K in solution. Upon mixing the freeze dried, essentially amorphous peptide powder in heavy water, the peptides self-assemble into long ribbon-like aggregates with a fixed cross section of circa 3x8 nm. It is still unclear whether this self-assembly is equilibrium like a surfactant micelle formation or whether it corresponds to a precipitation of a solid phase. Through light scattering measurements on dilution series, the solubility of the ribbons has been determined to 4.7 μM. However, quantitative NMR spectroscopy shows a monomer concentration of 3 mM, corresponding to a roughly 60 times supersaturation, and independent of the total concentration. Samples prepared directly at, or below this specific concentration shows no, or only minor signs of aggregation. In combination with a broad peak in high resolution 1H NMR spectroscopy we conclude that the formation of the A10K aggregates occurs through an intermediate state in equilibrium with the peptide monomers. Please click Additional Files below to see the full abstract

Two Dimensional Oblique Molecular Packing within a Model Peptide Ribbon Aggregate

A10K (A=alanine, K=lysine) model peptides self‐assemble into ribbon‐like β‐sheet aggregates. Here, we report an X‐ray diffraction investigation on a flow‐aligned dispersion of these self‐assembly structures. The two‐dimensional wide‐angle X‐ray scattering pattern suggests that peptide pack in a two‐dimensional oblique lattice, essentially identical to the crystalline packing of polyalanine, An (for n>4). One side of the oblique unit cell, corresponding to the anti‐parallel β‐sheet, is oriented along the ribbon's axis. Together with recently published small angle X‐ray scattering data of the same system, this work thus yields a detailed description of the self‐assembled ribbon aggregates, down to the molecular length scale. Notably, our results highlight the importance of the crystalline peptide packing within its self‐assembly aggregates, which is often neglected

Photovoltaik-Freiflächenanlagen und die Vernetzung von Lebensräumen an überörtlichen Verkehrswegen

Im Zuge der Energiewende werden zunehmend Photovoltaik-Freiflächenanlagen (PV-FFA) entlang von Verkehrswegen errichtet. Ziel des F+E-Vorhabens war es, die in Verbindung mit überörtlichen Verkehrswegen bestehenden PV-FFA in Hinblick auf die Eignung als Vernetzungselement und mögliche Konflikte in Bezug auf die Erhaltung der Durchlässigkeit der Landschaft zu untersuchen und Empfehlungen zu erarbeiten. Um Erkenntnisse zu den räumlich-funktionalen Beziehungen zwischen PV-FFA und umgebenden Habitaten zu gewinnen, wurde 2017 eine Fang-Wiederfang-Studie zu Tagfaltern durchgeführt. Es wurden insgesamt 23 Tagfalterarten, darunter auch gefährdete Arten, erfasst. Die meisten Arten bzw. Individuen wechselten im Untersuchungszeitraum mehrfach zwischen den Untersuchungsflächen. Insgesamt zeigte die Studie, dass die extensiv genutzten Betriebsflächen für zahlreiche Tagfalterarten einen (Teil)Lebensraum darstellen können, dessen Qualität maßgeblich von der Strukturvielfalt, dem Blütenangebot sowie der Anbindung an weitere Habitate abhängt. Um Aussagen zur Raumkonstellation und zum Landschaftskontext treffen zu können, wurden die Anlagen an Verkehrswegen bundesweit auf der Grundlage von Orthophotos erfasst und hinsichtlich ihrer Lage innerhalb der Lebensraumnetze für Wälder, Großsäuger sowie trockene und feuchte Offenlandlebensräume bewertet. Es wurden insgesamt 455 Anlagen ermittelt. Der Großteil der Anlagen (93 %) zeigte innerhalb eines 1000 m-Puffers Raumzusammenhänge mit funktional bedeutsamen Flächen der Lebensraumnetze. Eine gute Bewertung der Habitatqualität wiesen 20 % der Anlagen auf. Bei den übrigen Anlagen konnten aufgrund einer geringeren strukturellen Ausstattung nur einzelne Kriterien als gut bewertet. Die Umgebung der Anlagen war meist von intensiv genutzten Flächen (Acker und Intensivgrünland) geprägt, während naturnahes Offenland nie mehr als 35 % ausmachte. Anhand konkreter Beispiele wird gezeigt, dass die Anlagen zwar räumliche Konfliktpotenziale aufweisen, andererseits aber bei sorgfältiger Planung als funktionale Ergänzung des Straßenbegleitgrüns insbesondere in ausgeräumten Agrarlandschaften wirken können. Die im F+E-Vorhaben beschriebenen positiven Wirkungen für die Vernetzung müssen unter dem Gesichtspunkt gesehen werden, dass vielerorts keine naturnahen Lebensräume oder anderen (Rest-)Flächen mehr vorhanden sind, die diese Funktionen sonst übernehmen können

Detection of air trapping in chronic obstructive pulmonary disease by low frequency ultrasound

<p>Abstract</p> <p>Background</p> <p>Spirometry is regarded as the gold standard for the diagnosis of COPD, yet the condition is widely underdiagnosed. Therefore, additional screening methods that are easy to perform and to interpret are needed. Recently, we demonstrated that low frequency ultrasound (LFU) may be helpful for monitoring lung diseases. The objective of this study was to evaluate whether LFU can be used to detect air trapping in COPD. In addition, we evaluated the ability of LFU to detect the effects of short-acting bronchodilator medication.</p> <p>Methods</p> <p>Seventeen patients with COPD and 9 healthy subjects were examined by body plethysmography and LFU. Ultrasound frequencies ranging from 1 to 40 kHz were transmitted to the sternum and received at the back during inspiration and expiration. The high pass frequency was determined from the inspiratory and the expiratory signals and their difference termed ΔF. Measurements were repeated after inhalation of salbutamol.</p> <p>Results</p> <p>We found significant differences in ΔF between COPD subjects and healthy subjects. These differences were already significant at GOLD stage 1 and increased with the severity of COPD. Sensitivity for detection of GOLD stage 1 was 83% and for GOLD stages worse than 1 it was 91%. Bronchodilator effects could not be detected reliably.</p> <p>Conclusions</p> <p>We conclude that low frequency ultrasound is cost-effective, easy to perform and suitable for detecting air trapping. It might be useful in screening for COPD.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01080924">NCT01080924</a></p

Einführung des cloudbasierten Bibliothekssystems Alma in Berlin – ein Erfahrungsbericht

Die enge Zusammenarbeit der vier Berliner Universitätsbibliotheken [Freie Universität Berlin (FU), Humboldt-Universität zu Berlin (HU), Technische Universität Berlin (TU), Universität der Künste Berlin (UdK)] reicht weit zurück. Bereits vor der Jahrtausendwende haben die Berliner Universitätsbibliotheken (UBs) gemeinsam das Bibliothekssystem Aleph 500 ausgewählt und implementiert, danach folgten weitere Systeme – das Linking System SFX, die Digitale Bibliothek MetaLib und das Bibliotheksportal Primo. Es war daher folgerichtig und selbstverständlich, dass auch die Auswahl und Implementierung eines neuen Bibliothekssystems in enger Abstimmung und Zusammenarbeit erfolgte. Die Erfahrungen bei Vertragsverhandlungen und Implementierung von Alma sind Gegenstand des folgenden Berichtes.As regards implementing new library technology, the Berlin University libraries have been working closely together for more than 20 years. It was the case for the implementation of the legacy system Aleph 500, the linking system SFX, the digital library MetaLib and the library portal Primo, and therefore it was a matter of course to continue the close cooperation during the implementation of the new cloud-based library system, too. The experience gained during the contract negotiations and the implementation project, and lessons learned are the focus of this report.Peer Reviewe

Characterization of a rat osteotomy model with impaired healing

<p>Abstract</p> <p>Background</p> <p>Delayed union or nonunion are frequent and feared complications in fracture treatment. Animal models of impaired bone healing are rare. Moreover, specific descriptions are limited although understanding of the biological course of pathogenesis of fracture nonunion is essential for therapeutic approaches.</p> <p>Methods</p> <p>A rat tibial osteotomy model with subsequent intramedullary stabilization was performed. The healing progress of the osteotomy model was compared to a previously described closed fracture model. Histological analyses, biomechanical testing and radiological screening were undertaken during the observation period of 84 days (d) to verify the status of the healing process. In this context, particular attention was paid to a comparison of bone slices by histological and immunohistological (IHC) methods at early points in time, <it>i.e</it>. at 5 and 10 d post bone defect.</p> <p>Results</p> <p>In contrast to the closed fracture technique osteotomy led to delayed union or nonunion until 84 d post intervention. The dimensions of whole reactive callus and the amounts of vessels in defined regions of the callus differed significantly between osteotomized and fractured animals at 10 d post surgery. A lower fraction of newly formed bone and cartilaginous tissue was obvious during this period in osteotomized animals and more inflammatory cells were observed in the callus. Newly formed bone tissue accumulated slowly on the anterior tibial side with both techniques. New formation of reparative cartilage was obviously inhibited on the anterior side, the surgical approach side, in osteotomized animals only.</p> <p>Conclusion</p> <p>Tibial osteotomy with intramedullary stabilisation in rats leads to pronounced delayed union and nonunion until 84 d post intervention. The early onset of this delay can already be detected histologically within 10 d post surgery. Moreover, the osteotomy technique is associated with cellular and vascular signs of persistent inflammation within the first 10 d after bone defect and may be a contributory factor to impaired healing. The model would be excellent to test agents to promote fracture healing.</p