Обоснование выбора электродвигателя и схемы его включения для системы точного поддержания скорости

Рассматривается применение в системах точного поддержания скорости различных синхронных электродвигателей. В результате сравнения рекомендовано применение в таких системах конденсаторного синхронного реактивного двигателя с трехфазными обмотками статора. Это позволяет упростить и удешевить систему точного электропривода и повысить ее надежность

Glycoprotein (GP)96 is essential for maintaining intestinal epithelial architecture by supporting its self-renewal capacity

BACKGROUND & AIMS Glycoprotein (GP)96 is an endoplasmic reticulum (ER)-resident master chaperone for cell surface receptors including the Wnt co-receptors LRP5/6. Intestinal epithelial cells (IEC)-specific deletion of Gp96 is embryonically lethal. However, the role of GP96 in adult intestinal tissue and especially within the intestinal stem cell (ISC) niche has not been studied so far. Here, we investigated how GP96-loss interferes with intestinal homeostasis by compromising viability, proliferation and differentiation of IEC. METHODS Tamoxifen was used to induce Cre-mediated deletion of Gp96 in GP96-Villin$^{creERT2}$ mice and intestinal organoids. With H&E- and immunofluorescence staining we assessed alterations in intestinal morphology and the presence and localization of IEC-types. Real-time PCR and Western blot analysis were performed to explore the molecular mechanisms underlying the severe phenotype of Gp96 KO mice and organoids. RESULTS IEC-specific deletion of Gp96 in adult mice resulted in a rapid degeneration of the stem cell niche, followed by a complete eradication of the epithelial layer and death within few days. These effects were due to severe defects in ISC renewal and premature ISC differentiation, which resulted from defective Wnt and Notch signaling. Furthermore, depletion of GP96 led to massive induction of ER stress. While effects on ISC renewal and adequate differentiation were partly reversed upon activation of Wnt/Notch signaling, viability could not be restored, indicating that reduced viability was mediated by other mechanisms. CONCLUSIONS Our work demonstrates that GP96 plays a fundamental role in regulating ISC fate and epithelial regeneration and is therefore indispensable for maintaining intestinal epithelial homeostasis

Generation of Active Protein Phosphatase 2A Is Coupled to Holoenzyme Assembly

Protein phosphatase 2A (PP2A) is a prime example of the multisubunit architecture of protein serine/threonine phosphatases. Until substrate-specific PP2A holoenzymes assemble, a constitutively active, but nonspecific, catalytic C subunit would constitute a risk to the cell. While it has been assumed that the severe proliferation impairment of yeast lacking the structural PP2A subunit, TPD3, is due to the unrestricted activity of the C subunit, we recently obtained evidence for the existence of the C subunit in a low-activity conformation that requires the RRD/PTPA proteins for the switch into the active conformation. To study whether and how maturation of the C subunit is coupled with holoenzyme assembly, we analyzed PP2A biogenesis in yeast. Here we show that the generation of the catalytically active C subunit depends on the physical and functional interaction between RRD2 and the structural subunit, TPD3. The phenotype of the tpd3Δ strain is therefore caused by impaired, rather than increased, PP2A activity. TPD3/RRD2-dependent C subunit maturation is under the surveillance of the PP2A methylesterase, PPE1, which upon malfunction of PP2A biogenesis, prevents premature generation of the active C subunit and holoenzyme assembly by counteracting the untimely methylation of the C subunit. We propose a novel model of PP2A biogenesis in which a tightly controlled activation cascade protects cells from untargeted activity of the free catalytic PP2A subunit

Regulation of PP2A biogenesis in yeast

Proteinphosphatase 2A (PP2A) ist eine wichtige Serin-/Threoninphosphatase, die an vielen Prozessen in der Zelle beteiligt ist. Sie besteht aus einer katalytischen C Untereinheit, einer Strukturuntereinheit A und einer regulatorischen B-Typ Untereinheit. Hefe kann als Modelorganismus dienen, da PP2A hoch konserviert ist. Die Biogenese von PP2A ist ein komplexer und streng kontrollierter Prozess. Nach Generierung der C Untereinheit ist die Interaktion mit dem Aktivatorprotein PTPA/RRD nötig für den Konformationswechsel zu dem aktiven Enzym. Unsere Arbeitsgruppe konnte zeigen, dass die Maturation der C Untereinheit an den Holoenzymaufbau gekoppelt ist, da die Generierung einer katalytisch aktiven C Untereinheit von der physischen und funktionalen Interaktion zwischen RRD2 und der Strukturuntereinheit TPD3 abhängt. Außerdem wird der Aufbau des PP2A-Holoenzyms durch posttranslationale Modifikationen wie Phosphorylierung und Methylierung reguliert. Da sich die Hefe B-Typ Untereinheit CDC55 in einem hyperphosphorylierten Zustand ansammelt, wenn die Gene von RRD1/2 deletiert werden, haben wir CDC55 mittels Tandem Affinity Purification (TAP) aufgereinigt und Phosphorylierungsstellen mit Massenspektrometrie bestimmt. Weiters haben wir die Rolle der PP2A-spezifischen Methylesterase PPE1 untersucht. Wir konnten zeigen, dass der zu Grunde liegende molekulare Mechanismus der PPE1-Funktion von ihrer Methylesterase-Aktivität abhängt, während dafür weder die Bildung eines stabilen Komplexes zwischen PPE1 und der C Untereinheit nötig ist, noch ein „Metallentfernungs-Loop“ zur Inhibierung der PP2A C Untereinheit beteiligt ist. Unsere Ergebnisse deuten darauf hin, dass PPE1 eine höhere Affinität gegenüber einer unreifen C Untereinheit im Vergleich zu einer C Untereinheit hat, die sich in einem reifen trimeren Komplex befindet, was darauf schließen lässt, dass PPE1 eine wichtige Funktion in der „Qualitätskontrolle“ der frühen PP2A-Biogenese ausübt.Protein Phosphatase 2A (PP2A) is a major phosphoserine/threonine phosphatase involved in many cellular processes. It consists of a catalytic C subunit, a structural A subunit and a regulatory B-type subunit. As PP2A is highly conserved, yeast can serve as a model organism. PP2A biogenesis is a complex and tightly controlled process. Upon generation of the C subunit, the interaction with the activator protein PTPA/RRD seems to be required for the conformational switch into the active enzyme. Our research group could demonstrate that the maturation of the C subunit is coupled to holoenzyme assembly, as generation of a catalytically active C subunit depends on the physical and functional interaction between the activator protein PTPA/RRD and the structural A subunit TPD3. Moreover, PP2A holoenzyme assembly is regulated via posttranslational modifications such as phosphorylation and methylation. As the yeast B-type subunit CDC55 accumulates in a hyperphosphorylated state upon deletion of the activator genes RRD1/2, we purified CDC55 using the tandem affinity purification (TAP) procedure and determined phosphorylation sites by mass spectrometry (MS). Furthermore, we studied the role the PP2A-specific methylesterase PPE1. We could show that the underlying molecular mechanism of PPE1 function depends on its methylesterase activity, whereas neither stable complex formation between PPE1 and the C subunit is required nor a “metal eviction loop” for inhibition of the PP2A catalytic activity. Our results indicate that PPE1 has a higher affinity towards an immature C subunit compared to C in a mature, trimeric complex containing a regulatory B subunit supporting the notion that PPE1 has an important “quality control” function early in PP2A biogenesis.eingereicht von Claudia StanzelAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in dt. SpracheWien, Univ. für Bodenkultur, Diss., 2012OeBB(VLID)193068

Portable NIV for patients with moderate to severe COPD: two randomized crossover trials

Background!#!Long-term non-invasive ventilation (NIV) is as an established treatment option for chronic hypercapnic COPD patients. Beneficial effects have also been shown during exercise, but this is restricted to rehabilitation programs. New portable NIV (pNIV) devices may now enable NIV application during walking at home.!##!Study design and methods!#!In two randomized crossover trials, the impact of pNIV on dyspnea and endurance capacity was investigated in patients with moderate to severe COPD. Participants performed a standardized 6-min walking test, with and without pNIV, using a pre-set inspiratory/expiratory positive airway pressure of 18/8 cmH!##!Results!#!38 patients (66.9 ± 7.4 years, mean FEV!##!Interpretation!#!The use of a pNIV device during walking can improve dyspnea and walking distance in patients with moderate to severe COPD. Patients who do not already receive long-term NIV therapy are more likely to benefit compared to those undergoing long-term NIV. Careful patient selection is mandatory. Clinical Trial Register: DRKS00013203; DRKS00012913 registered October 20th 2017 and October 16th 2017; https://www.drks.de/drks_web/

Doxycycline, metronidazole and isotretinoin: Do they modify microRNA/mRNA expression profiles and function in murine T-cells?

Inflammatory bowel disease (IBD) may develop due to an inflammatory response to commensal gut microbiota triggered by environmental factors in a genetically susceptible host. Isotretinoin (acne therapy) has been inconsistently associated with IBD onset and flares but prior treatment with antibiotics, also associated with IBD development, complicates the confirmation of this association. Here we studied in mice whether doxycycline, metronidazole or isotretinoin induce epigenetic modifications, and consequently change T-cell mRNA expression and/or function directly after treatment and after a 4 week recovery period. Isotretinoin induced IL-10 signaling in Tregs and naive T-cells directly after treatment and reduced effector T-cell proliferation alone and in co-culture with Tregs. Metronidazole activated processes associated with anti-inflammatory pathways in both T-cell subsets directly after the treatment period whereas doxycycline induced an immediate pro-inflammatory expression profile that resolved after the recovery period. Long-term changes indicated an inhibition of proliferation by doxycycline and induction of beneficial immune and metabolic pathways by metronidazole. Persistent alterations in microRNA and mRNA expression profiles after the recovery period indicate that all three medications may induce long-term epigenetic modifications in both T-cell subsets. Yet, our data do not support the induction of a long-term pro-inflammatory phenotype in murine Tregs and naive T-cells