Macroscopic transport by synthetic molecular machines

Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with—and perform physical tasks in—the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (‘molecular shuttles’) to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.

Purkinje cell-specific ablation of CaV2.1 Channels is sufficient to cause cerebellar ataxia in mice

The Cacna1a gene encodes the α1A subunit of voltage-gated CaV2.1 Ca2+ channels that are involved in neurotransmission at central synapses. CaV2.1-α1- knockout (α1KO) mice, which lack CaV2.1 channels in all neurons, have a very severe phenotype of cerebellar ataxia and dystonia, and usually die around postnatal day 20. This early lethality, combined with the wide expression of CaV2.1 channels throughout the cerebellar cortex and nuclei, prohibited determination of the contribution of particular cerebellar cell types to the development of the severe neurobiological phenotype in Cacna1a mutant mice. Here, we crossed conditional Cacna1a mice with transgenic mice expressing Cre recombinase, driven by the Purkinje cell-specific Pcp2 promoter, to specifically ablate the CaV2.1- α1A subunit and thereby CaV2.1 channels in Purkinje cells. Purkinje cell CaV2.1-α1A-knockout (PCα1KO) mice aged without difficulties, rescuing the lethal phenotype seen in α1KO mice. PCα1KO mice exhibited cerebellar ataxia starting around P12, much earlier than the first signs of progressive Purkinje cell loss, which appears in these mice between P30 and P45. Secondary cell loss was observed in the granular and molecular layers of the cerebellum and the volume of all individual cerebellar nuclei was reduced. In this mouse model with a cell type-specific ablation of CaV2.1 channels, we show that ablation of CaV2.1 channels restricted to Purkinje cells is sufficient to cause cerebellar ataxia. We demonstrate that spatial ablation of CaV2.1 channels may help in unraveling mechanisms of human disease

Light Dose is a Limiting Factor to Maintain Cell Viability in Fluorescence Microscopy and Single Molecule Detection

A test system for cell viability based on colony formation has been established and applied to high resolution fluorescence microscopy and single molecule detection. Living cells were irradiated either by epi-illumination or by total internal reflection (TIR) of a laser beam, and light doses where at least 90% of irradiated cells survived were determined. These light doses were in the range of a few J/cm2 up to about 200 J/cm2 depending on the wavelength of illumination as well as on the presence or absence of a fluorescent dye (e.g., the membrane marker laurdan). In general, cells were less sensitive to TIR than to epi-illumination. However, comparably high light doses needed for repetitive excitation of single molecules limit the application of super-resolution microscopy to living cells

Changes of peripheral T cell subsets in melanoma patients with immune-related adverse events

IntroductionImmunotherapies have improved the prognosis of many cancer patients including patients with advanced melanoma. Immune checkpoint receptors including CTLA-4 and PD-1 have been established as main therapeutic targets for immunotherapy of melanoma. Although monotherapy is effective in melanoma patients, a dual therapy approach has been shown to be most effective. Dual checkpoint blockade, however, increases substantially the risk for immune-related adverse events (irAEs).MethodsIn this study, we characterized peripheral immune cell subsets in patients with anti-PD-1 monotherapy and with dual immune receptors blockade targeting PD-1 and CTLA-4.ResultsWe found differences in peripheral T cells between patients who developed severe immune-related side effects and patients with mild irAEs. We identified several mainly changes in CD8+ T cell subsets in patients with severe irAE under dual PD-1 and CTLA-4 blockade.DiscussionThis work suggests that peripheral immune cell dynamics could be associated with severe immune-related side effects in patients receiving immune checkpoint inhibitors. These changes could be used as future biomarkers in early diagnosis of irAEs

Evaluation der Maßnahmen zur Umsetzung der Vorschläge der Hartz-Kommission: Modul 1a, Neuausrichtung der Vermittlungsprozesse ; Bericht 2005 für das Bundesministerium für Wirtschaft und Arbeit

"Das Bundesministerium für Wirtschaft und Arbeit hat das Wissenschaftszentrum Berlin für Sozialforschung und das infas Institut für angewandte Sozialwissenschaft im September 2004 mit dem Evaluationsvorhaben Arbeitspaket 1, 'Modul 1a Neuausrichtung der Vermittlungsprozesse' beauftragt. Im Mittelpunkt steht die zentrale Frage, ob eine 'Verbesserung der Qualität und Schnelligkeit der Arbeitsvermittlung' nachgewiesen werden kann, die auf die Reformgesetze und -maßnahmen zurückzuführen sind. Implementationsanalysen untersuchen die Praxis der Agenturen bezüglich Bewerberdifferenzierung, Kundenmanagement, Aktivierung sowie Neuregelung von Zumutbarkeit und Sperrzeiten sowie die Vermittlungsdienstleistungen an Arbeitgeber. Auch der Einsatz vermittlungsnaher Dienstleistungen (Einschaltung Dritter nach Paragraph 37, Eingliederungsmaßnahmen durch Träger Paragraph 421i, Vermittlungsgutscheine, Personal-Service-Agenturen -PSA-) wird unter Umsetzungsgesichtspunkten untersucht. Über die Vermittlungsorganisation in Arbeitsgemeinschaften nach Paragraph 44b SGB II liegen erste Ergebnisse einer Grunderhebung vor. Die mittels Fallstudien, Dokumentenanalyse, schriftlichen und telefonischen Erhebungen gewonnenen Ergebnisse umreißen den Stand der Neuausrichtung der Vermittlungsprozesse. Die Wirkung der neu ausgerichteten Vermittlungsprozesse werden unter zwei Gesichtspunkten untersucht. Mittels multivariater Auswertungen wird zum einen die Wirkung des Kundenzentrums auf die Abgänge aus Arbeitslosigkeit geprüft. In einer instrumentenspezifisch angelegten Wirkungsanalyse wird zum anderen die Effektivität von vermittlungsnahen Dienstleistungen (Beauftragung Dritter, Beauftragung von Trägern mit Eingliederungsmaßnahmen, Personal Service Agenturen, Vermittlungsgutschein) analysiert und eine entsprechende Kosten-Nutzen-Bewertung vorgenommen. Der Bericht 2005 legt die Ergebnisse nach neun Monaten Laufzeit des Evaluationsvorhabens vor. Er ist vom Bemühen getragen, bereits belastbare Ergebnisse nach diesem vergleichsweise kurzen Zeitraum vorzulegen. Die Berichterstattung steht allerdings unter dem deutlichen Hinweis, dass die Organisation der Vermittlungsprozesse in den Agenturen und Arbeitsgemeinschaften weiterhin im Fluss ist. Die Implementationsstudien versuchen deswegen über die Momentaufnahme hinaus, grundlegende Konstruktionsfragen und -probleme aufzuzeigen. Wegen des vergleichsweise kurzen Beobachtungszeitraums seit Einführung der Kundenzentren und der vermittlungsnahen Dienstleistungen stehen auch die Wirkungsanalysen noch unter Vorbehalten." (Textauszug

Crystal Structure of the FeS Cluster–Containing Nucleotide Excision Repair Helicase XPD

DNA damage recognition by the nucleotide excision repair pathway requires an initial step identifying helical distortions in the DNA and a proofreading step verifying the presence of a lesion. This proofreading step is accomplished in eukaryotes by the TFIIH complex. The critical damage recognition component of TFIIH is the XPD protein, a DNA helicase that unwinds DNA and identifies the damage. Here, we describe the crystal structure of an archaeal XPD protein with high sequence identity to the human XPD protein that reveals how the structural helicase framework is combined with additional elements for strand separation and DNA scanning. Two RecA-like helicase domains are complemented by a 4Fe4S cluster domain, which has been implicated in damage recognition, and an α-helical domain. The first helicase domain together with the helical and 4Fe4S-cluster–containing domains form a central hole with a diameter sufficient in size to allow passage of a single stranded DNA. Based on our results, we suggest a model of how DNA is bound to the XPD protein, and can rationalize several of the mutations in the human XPD gene that lead to one of three severe diseases, xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy

Synthetic Biology of Proteins: Tuning GFPs Folding and Stability with Fluoroproline

Proline residues affect protein folding and stability via cis/trans isomerization of peptide bonds and by the C(gamma)-exo or -endo puckering of their pyrrolidine rings. Peptide bond conformation as well as puckering propensity can be manipulated by proper choice of ring substituents, e.g. C(gamma)-fluorination. Synthetic chemistry has routinely exploited ring-substituted proline analogs in order to change, modulate or control folding and stability of peptides.In order to transmit this synthetic strategy to complex proteins, the ten proline residues of enhanced green fluorescent protein (EGFP) were globally replaced by (4R)- and (4S)-fluoroprolines (FPro). By this approach, we expected to affect the cis/trans peptidyl-proline bond isomerization and pyrrolidine ring puckering, which are responsible for the slow folding of this protein. Expression of both protein variants occurred at levels comparable to the parent protein, but the (4R)-FPro-EGFP resulted in irreversibly unfolded inclusion bodies, whereas the (4S)-FPro-EGFP led to a soluble fluorescent protein. Upon thermal denaturation, refolding of this variant occurs at significantly higher rates than the parent EGFP. Comparative inspection of the X-ray structures of EGFP and (4S)-FPro-EGFP allowed to correlate the significantly improved refolding with the C(gamma)-endo puckering of the pyrrolidine rings, which is favored by 4S-fluorination, and to lesser extents with the cis/trans isomerization of the prolines.We discovered that the folding rates and stability of GFP are affected to a lesser extent by cis/trans isomerization of the proline bonds than by the puckering of pyrrolidine rings. In the C(gamma)-endo conformation the fluorine atoms are positioned in the structural context of the GFP such that a network of favorable local interactions is established. From these results the combined use of synthetic amino acids along with detailed structural knowledge and existing protein engineering methods can be envisioned as a promising strategy for the design of complex tailor-made proteins and even cellular structures of superior properties compared to the native forms

The German National Registry of Primary Immunodeficiencies (2012-2017)

Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1–25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0–88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE- syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%—subcutaneous; 29%—intravenous; 1%—unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment