A Phenomenological Study on the Experiences of Middle-Class Parents Facilitating Homework

This study explored middle-class parents’ descriptions of their experience of the emotional “essence” of the conflicts that arose between themselves and their children as parents facilitated the homework process. This study on homework experiences sought to gain a deeper understanding and meaning experienced firsthand from the middle-class parents’ point of view. The use of phenomenological methods allowed for the deep and thick description necessary to uncover the essence of the middle-class parental perspectives on the parent-child emotional experience embedded in the homework process. The identified themes included creation of a homework routine, emotions of resistance and stress, and parental role construction. The emergent constituents were: paradox of parental role construction, tiers of stress, and desire for family harmony during homework time. The study revealed the following ramifications resulting from the relationships between emergent themes and constituents: the intersections between paradox of parental role construction and desire for family harmony, desire for family harmony and creation of a homework routine, creation of a homework routine and paradox of parental role construction and, finally, desire for family harmony and tiers of stress. These intersections manifested in the following: stress, resistance, confusion, and family tension, respectively. The significance of this study rests in its extension of current research on the experience of homework facilitation among working-class families with elementary-aged children by focusing on learning at home in the middle-class. It identified stress during this period as tiered, that middle-class parents would like training on their role during homework, and that middle-class parents had a cathartic stress-relieving experience when they were given an opportunity to share their “homework” experiences

Measurement management system

Předmětem diplomové práce je analýza normy ČSN EN ISO 10012 se zaměřením na měření drsnosti. Práce byla vypracována ve spolupráci se soukromou firmou PLASMAMETAL s.r.o. se sídlem v Brně, která se zabývá povrchovými úpravami materiálů. Podstatnou součástí práce je manuál ke zlepšení systému managementu měření ve firmě. Jsou uváženy i ekonomické aspekty související s nákupem nového měřícího vybavení.The subject of diploma thesis is analysis of the European Standard EN ISO 10012, which has a status of a Czech Standard (ČSN EN ISO 10012). It’s focused on roughness measurement. The thesis was written in cooperation with a private company called PLASMAMETAL Ltd. situated in Brno. The company offers coating applications for a variety of materials. Important part of the thesis is a measurement management system improvement manual for PLASMAMETAL Ltd. It’s also dealt with the economical aspect of an investement into a new measurement equipment.

Influence of selenium on pancreatic carcinogenesis and the role of the selenoproteins cytosolic and mitochondrial thioredoxin reductase in the pancreas

Pancreatic ductal adenocarcinoma (PDA) is one of the most aggressive cancers in humans. It is the fourth leading cause of cancer related deaths in Germany and in the United States. Most PDA occurs sporadically, but there are also approximately 5-10% of patients with a family history of pancreatic cancer. The high mortality of PDA is attributed to a lack of early detection methods and poor efficacy in therapies for advanced disease. As an alternative, preventive strategies in individuals with familial pancreatic carcinoma should be considered. Several epidemiological studies showed an inverse correlation between selenium-intake and mortality of certain types of cancer and particularly in gastrointestinal cancers. To this end, in the first part of this study, the influence of selenium as a preventive nutritional additive was investigated in a genetically defined pancreatic cancer mouse model, the EL-TGFatg/+;p53+/- mouse strain. As a major finding, the differentiation grade of the pancreatic carcinomas was heavily influenced by the selenium status. In the selenium-deficient group there were more non-differentiated pancreatic carcinomas than in the selenium-adequate group, which highlighted the implication of selenium or selenoproteins in tumour differentiation. Unexpectedly, however, there was no protective effect of selenium on total or pancreatic tumour latency. Within the selenoproteins, the thioredoxin reductases are strong candidates which may influence cell death and differentiation in pancreatic carcinogenesis. Their function is generally associated with tumour proliferation and also linked to the activation of the tumour suppressor p53. Consequently, the role of the thioredoxin reductases in the pancreas was studied in the second part of this thesis. The enzymatic activity of cytosolic (TXNRD1) and mitochondrial (TXNRD2) thioredoxin reductase in the pancreas and other organs was determined in relation to the selenium-status. TXNRD1 activity in the pancreas was moderate and decreased under selenium deficiency. TXNRD2, instead, showed very high pancreatic activity in relation to other organs and its activity was even increased under selenium-deficiency emphasising its special role in this organ. To further investigate the function of Txnrd1 and Txnrd2 in the pancreas, tissue-specific knockout mice were created and characterized. The Txnrd1 knockout mice did not show an overt phenotype. Interestingly although, pancreatic acinus cells in one year old mice showed a disturbed rough endoplasmic reticulum and alterations in serum amylase and lipase. These mice also had an impaired glucose tolerance. The pancreas of Txnrd2 knockout mice showed severe chronic pancreatitis and pancreatic atrophy at the end of an observation period of one year. The progressive pathogenic process started with mild pancreatitis, developing spontaneously at an age of four weeks. The chronic stage was characterized by the formation of different types of acinar-to-ductal metaplastic lesions, which could be classified in part as early precursor lesions of pancreatic carcinomas. The endocrine pancreas was not affected. The pancreas-specific Txnrd2 knockout mouse strain is the first genetically modified mouse model spontaneously developing acute and chronic pancreatitis. This strain constitutes a unique and powerful tool to model pancreatic pathogenesis, especially the yet unresolved process of transformation from inflammatory to malignant disease.Das duktale Adenokarzinom des Pankreas gehört zu den aggressivsten Krebsarten des Menschen. In Deutschland wie auch in den USA bilden Krebserkrankungen des Pankreas die viert häufigste durch Krebs hervorgerufene Todesursache. Obwohl die molekularen Mechanismen des duktalen Adenokarzinoms immer besser verstanden werden, nimmt diese Krebserkrankung meist einen tödlichen Verlauf. Die hohe Sterblichkeitsrate wird vor allem durch fehlende Möglichkeiten der Früherkennung und mangelnde Effektivität der Behandlungsmethoden bei fortgeschrittener Krankheit begründet. Zumeist tritt das Pankreaskarzinom spontan auf, jedoch bei 5-10% der Patienten lässt sich ein familiärer Hintergrund nachweisen. Für diese Patientengruppe sollten präventive Maßnahmen angestrebt werden. In epidemiologischen Studien konnten Hinweise zu einer inversen Korrelation von Selenaufnahme und altersabhängiger Sterblichkeit bei verschiedenen Krebsarten und vor allem bei gastrointestinalen Krebserkrankungen erarbeitet werden. Im ersten Teil der hier vorliegenden Studie wurde daher der Einfluss von Selen auf das Pankreaskarzinom des genetisch definierten EL-TGFatg/+;p53+/- Mausmodelles beforscht. Selen-defiziente Mäuse wurden mit Selen-adäquat ernährten Mäusen verglichen. Interessanter Weise wurde der Differenzierungsgrad der entstandenen Pankreas-karzinome hoch signifikant durch den Selenstatus der Mäuse beeinflusst. Selen-defizient ernährte Mäuse entwickelten hauptsächlich anaplastische Pankreaskarzinome, wohingegen Selen-adäquat ernährte Mäuse mehr differenzierte Tumoren aufwiesen. Unerwarteter Weise konnte jedoch kein protektiver Einfluss von Selen weder auf die Latenzzeit aller auftretender Tumoren, noch im einzelnen auf Pankreaskarzinome festgestellt werden. Innerhalb der Gruppe der Selenoproteine sind die Thioredoxinreduktasen potentielle Kandidaten welche den Zelltod und die Differenzierung von Pankreaskarzinomen beeinflussen. Ihre Funktion wird im Allgemeinen mit der Proliferation von Tumoren und der Aktivierung des Tumorsupressors p53 in Verbindung gebracht. Folglich wurde die Rolle der Thioredoxinreduktasen im Pankreas im zweiten Teil dieser Studie bearbeitet. Die enzymatische Aktivität der cytosolischen (TXNRD1) und mitochondrialen (TXNRD2) Thioredoxinreduktase im Pankreas und anderen Organen wurde im Allgemeinen und in Bezug auf den Selenstatus der Tiere bestimmt. Die enzymatische Aktivität von TXNRD1 im Pankreas war eher mäßig und sank unter Selen-defizienten Bedingungen noch weiter ab. TXNRD2 hingegen zeigte eine sehr starke enzymatische Aktivität im Pankreas und in Selen-defizienten Tieren erhöhte sich die enzymatische Aktivität von TXNRD2 im Pankreas sogar noch, was auf eine wichtige Rolle dieses Enzyms in diesem Organ schließen lässt. Um die Rolle von Txnrd1 und Txnrd2 im Pankreas aufzuklären wurden Gewebe-spezifische Knockout-Mäuse gezüchtet und charakterisiert. Txnrd1 Knockout-Mäuse zeigten zuerst keinen offensichtlichen Phänotyp. Interessanter Weise jedoch, konnte in Azinus-Zellen des Pankreas von ein Jahr alten Mäusen ein dilatatives bis hin zu völlig zerstörtem rauen Endoplasmatischem Retikulum beobachtet werden. Des Weiteren wurden Veränderungen der Amylase und Lipase Werte im Blutserum gemessen. Die Tiere hatten auch eine veränderte Glucose Toleranz. Das Pankreas der Txnrd2 Knockout-Mäuse wies eine schwerwiegende chronische Pankreatitis und voranschreitende Atrophie des Pankreasgewebes gegen Ende des Beobachtungszeitraums von einem Jahr auf. Die Mäuse entwickelten spontan eine akute Pankreatitis im Alter von vier Wochen. In der chronischen Pankreatitis wurden verschiedene Arten von azinären-duktalen Metaplasien gefunden, die zum Teil als frühe Vorläuferstadien von Pankreaskarzinomen klassifiziert werden konnten. Das endokrine Pankreas wies keine Veränderungen auf. Dieser Pankreas-spezifische Txnrd2 Knockout-Mausstamm ist das erste genetische Model welches spontan akute und chronische Pankreatitis entwickelt und bietet daher enorme Möglichkeiten für die Erforschung dieser inflamatorischen Erkrankung und ihrer Verbindung zu Krebserkrankungen des Pankreas

Expression of a catalytically inactive mutant form of glutathione peroxidase 4 (Gpx4) confers a dominant-negative effect in male fertility.

The selenoenzyme Gpx4 is essential for early embryogenesis and cell viability for its unique function to prevent phospholipid oxidation. Recently, the cytosolic form of Gpx4 was identified as an upstream regulator of a novel form of non-apoptotic cell death, called ferroptosis, whereas the mitochondrial isoform of Gpx4 (mGpx4) was previously shown to be crucial for male fertility. Here, we generated and analyzed mice with targeted mutation of the active site selenocysteine (Sec) of Gpx4 (Gpx4_U46S). Mice homozygous for Gpx4_U46S died at the same embryonic stage (E7.5) as Gpx4-/- embryos as expected. Surprisingly, male mice heterozygous for Gpx4_U46S presented subfertility. Subfertility was manifested in a reduced number of litters from heterozygous breedings and an impairment of spermatozoa to fertilize oocytes in vitro. Morphologically, sperm isolated from heterozygous Gpx4_U46S mice revealed many structural abnormalities particularly in the spermatozoan midpiece due to improper oxidation and polymerization of sperm capsular proteins and malformation of the mitochondrial capsule surrounding and stabilizing sperm mitochondria. These findings are reminiscent of sperm isolated from selenium-deprived rodents or from mice specifically lacking mGpx4. Due to a strongly facilitated incorporation of Ser in the polypeptide chain as compared to Sec at the UGA codon, expression of the catalytically inactive Gpx4_U46S was found to be strongly increased. Since the stability of the mitochondrial capsule of mature spermatozoa depends on the moonlighting function of Gpx4 both as an enzyme oxidizing capsular protein thiols and being a structural protein, tightly controlled expression of functional Gpx4 emerges being key for full male fertility

Loss of Npn1 from motor neurons causes postnatal deficits independent from Sema3A signaling

AbstractThe correct wiring of neuronal circuits is of crucial importance for the function of the vertebrate nervous system. Guidance cues like the neuropilin receptors (Npn) and their ligands, the semaphorins (Sema) provide a tight spatiotemporal control of sensory and motor axon growth and guidance. Among this family of guidance partners the Sema3A-Npn1 interaction has been shown to be of great importance, since defective signaling leads to wiring deficits and defasciculation. For the embryonic stage these defects have been well described, however, also after birth the organism can adapt to new challenges by compensational mechanisms. Therefore, we used the mouse lines Olig2-Cre;Npn1cond and Npn1Sema− to investigate how postnatal organisms cope with the loss of Npn1 selectively from motor neurons or a systemic dysfunctional Sema3A-Npn1 signaling in the entire organism, respectively. While in Olig2-Cre+;Npn1cond−/− mice clear anatomical deficits in paw posturing, bone structure, as well as muscle and nerve composition became evident, Npn1Sema− mutants appeared anatomically normal. Furthermore, Olig2-Cre+;Npn1cond mutants revealed a dysfunctional extensor muscle innervation after single-train stimulation of the N.radial. Interestingly, these mice did not show obvious deficits in voluntary locomotion, however, skilled motor function was affected. In contrast, Npn1Sema− mutants were less affected in all behavioral tests and able to improve their performance over time. Our data suggest that loss of Sema3A-Npn1 signaling is not the only cause for the observed deficits in Olig2-Cre+;Npn1cond−/− mice and that additional, yet unknown binding partners for Npn1 may be involved that allow Npn1Sema− mutants to compensate for their developmental deficits

High STEAP1 expression is associated with improved outcome of Ewing's sarcoma patients

Background Ewing's sarcoma (ES) is the second most common bone or soft-tissue sarcoma in childhood and adolescence and features a high propensity to metastasize. The six-transmembrane epithelial antigen of the prostate 1 (STEAP1) is a membrane-bound mesenchymal stem cell marker highly expressed in ES. Here, we investigated the role of STEAP1 as an immunohistological marker for outcome prediction in patients with ES. Patients and methods Membranous STEAP1 immunoreactivity was analyzed using immunohistochemistry in 114 primary pre-chemotherapy ES of patients diagnosed from 1983 to 2010 and compared with clinical parameters and patient outcome. Median follow-up was 3.85 years (range 0.43-17.51). Results A total of 62.3% of the ES samples displayed detectable STEAP1 expression with predominant localization of the protein at the plasma membrane. High membranous STEAP1 immunoreactivity was found in 53.5%, which correlated with better overall survival (P=0.021). Accordingly, no or low membranous STEAP1 expression was identified as an independent risk factor in multivariate analysis (hazard ratio 2.65, P=0.036). Conclusion High membranous STEAP1 expression predicts improved outcome and may help to define a specific subgroup of ES patients, who might benefit from adapted therapy regimen

Diabetes causes marked inhibition of mitochondrial metabolism in pancreatic β-cells

Diabetes is a global health problem caused primarily by the inability of pancreatic β-cells to secrete adequate levels of insulin. The molecular mechanisms underlying the progressive failure of β-cells to respond to glucose in type-2 diabetes remain unresolved. Using a combination of transcriptomics and proteomics, we find significant dysregulation of major metabolic pathways in islets of diabetic βV59M mice, a non-obese, eulipidaemic diabetes model. Multiple genes/proteins involved in glycolysis/gluconeogenesis are upregulated, whereas those involved in oxidative phosphorylation are downregulated. In isolated islets, glucose-induced increases in NADH and ATP are impaired and both oxidative and glycolytic glucose metabolism are reduced. INS-1 β-cells cultured chronically at high glucose show similar changes in protein expression and reduced glucose-stimulated oxygen consumption: targeted metabolomics reveals impaired metabolism. These data indicate hyperglycaemia induces metabolic changes in β-cells that markedly reduce mitochondrial metabolism and ATP synthesis. We propose this underlies the progressive failure of β-cells in diabetes.Peer reviewe

Croconaine-based nanoparticles enable efficient optoacoustic imaging of murine brain tumors

Contrast enhancement in optoacoustic (photoacoustic) imaging can be achieved with agents that exhibit high absorption cross-sections, high photostability, low quantum yield, low toxicity, and preferential bio-distribution and clearance profiles. Based on advantageous photophysical properties of croconaine dyes, we explored croconaine-based nanoparticles (CR780RGD-NPs) as highly efficient contrast agents for targeted optoacoustic imaging of challenging preclinical tumor targets. Initial characterization of the CR780 dye was followed by modifications using polyethylene glycol and the cancer-targeting c(RGDyC) peptide, resulting in self-assembled ultrasmall particles with long circulation time and active tumor targeting. Preferential bio-distribution was demonstrated in orthotopic mouse brain tumor models by multispectral optoacoustic tomography (MSOT) imaging and histological analysis. Our findings showcase particle accumulation in brain tumors with sustainable strong optoacoustic signals and minimal toxic side effects. This work points to CR780RGD-NPs as a promising optoacoustic contrast agent for potential use in the diagnosis and image-guided resection of brain tumors

Benchmark datasets for 3D MALDI- and DESI-imaging mass spectrometry

BACKGROUND: Three-dimensional (3D) imaging mass spectrometry (MS) is an analytical chemistry technique for the 3D molecular analysis of a tissue specimen, entire organ, or microbial colonies on an agar plate. 3D-imaging MS has unique advantages over existing 3D imaging techniques, offers novel perspectives for understanding the spatial organization of biological processes, and has growing potential to be introduced into routine use in both biology and medicine. Owing to the sheer quantity of data generated, the visualization, analysis, and interpretation of 3D imaging MS data remain a significant challenge. Bioinformatics research in this field is hampered by the lack of publicly available benchmark datasets needed to evaluate and compare algorithms. FINDINGS: High-quality 3D imaging MS datasets from different biological systems at several labs were acquired, supplied with overview images and scripts demonstrating how to read them, and deposited into MetaboLights, an open repository for metabolomics data. 3D imaging MS data were collected from five samples using two types of 3D imaging MS. 3D matrix-assisted laser desorption/ionization imaging (MALDI) MS data were collected from murine pancreas, murine kidney, human oral squamous cell carcinoma, and interacting microbial colonies cultured in Petri dishes. 3D desorption electrospray ionization (DESI) imaging MS data were collected from a human colorectal adenocarcinoma. CONCLUSIONS: With the aim to stimulate computational research in the field of computational 3D imaging MS, selected high-quality 3D imaging MS datasets are provided that could be used by algorithm developers as benchmark datasets

Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis

open24siSelenoproteins are rare proteins among all kingdoms of life containing the 21st amino acid, selenocysteine. Selenocysteine resembles cysteine, differing only by the substitution of selenium for sulfur. Yet the actual advantage of selenolate- versus thiolate-based catalysis has remained enigmatic, as most of the known selenoproteins also exist as cysteine-containing homologs. Here, we demonstrate that selenolate-based catalysis of the essential mammalian selenoprotein GPX4 is unexpectedly dispensable for normal embryogenesis. Yet the survival of a specific type of interneurons emerges to exclusively depend on selenocysteine-containing GPX4, thereby preventing fatal epileptic seizures. Mechanistically, selenocysteine utilization by GPX4 confers exquisite resistance to irreversible overoxidation as cells expressing a cysteine variant are highly sensitive toward peroxide-induced ferroptosis. Remarkably, concomitant deletion of all selenoproteins in Gpx4cys/cys cells revealed that selenoproteins are dispensable for cell viability provided partial GPX4 activity is retained. Conclusively, 200 years after its discovery, a specific and indispensable role for selenium is provided.openIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, MarcusIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, Marcu