Wirkungsquerschnitte zur Bildung von Aktivierungsprodukten in Wechselwirkung von Protonen mit biologisch relevanten Elementen und Kollimatormaterialien im Energiebereich bis 200 MeV

Es wurden Anregungsfunktionen einiger protoneninduzierter Reaktionen an Kohlenstoff, Stickstoff, Sauerstoff, Blei und Titan mit Hilfe der Folienstapeltechnik im Energiebereich bis 200 MeV gemessen. Anhand der ermittelten Wirkungs-querschnitte wurde die Aktivierung von menschlichem Gewebe und der Strahlkollimatoren abgeschätzt. Im Rahmen der vorliegenden Arbeit wurde die Bildung der kurzlebigen Positronenstrahler 11C (T1/2 = 20,38 min) und 13N (T1/2 = 9,96 min), die bei der Bestrahlung der biologisch relevanten Elemente C, N und O mit Protonen intermediärer Energien entstehen, bestimmt. Die Aktivität wurde zerstörungsfrei g-spektrometrisch untersucht. Dabei wurde durch die Analyse der Zerfallskurven der Vernichtungsstrahlung die Aktivität des einzelnen b+-Emitters bestimmt. Um die Reaktionsmechanismen zu verdeutlichen wurden Kernmodellrechnungen mit dem Rechencode ALICE-IPPE für intermediäre Energie durchgeführt. Die Wirkungsquerschnitte für die natTi(p,x)45Ca, natTi(p,x)49V und natPb(p,x)204Tl Reaktionen konnten zum ersten Mal gemessen werden. Zur Herstellung dünner Messpräparate wurden radiochemische Trennmethoden ausgearbeitet. Zur Bestimmung der Radionuklidaktivitäten wurde b--Zählung und Röntgenspektrometrie eingesetzt. Die ermittelten Daten wurden ebenfalls mit den Ergebnissen der theoretischen Rechnungen verglichen. Die zusätzliche Dosis durch die kurzlebigen Positronenstrahler 11C und 13N wurde für Muskel-, Fett- und Knochengewebe ermittelt. Die Berechnungen zeigen, dass der Beitrag der Positronenemitter nicht vernachlässigbar ist. Bei der Bestrahlung von Tumorgewebe entstehen im bestrahlten Volumen bis zu 35 % der eingesetzten Strahlendosis. Aktivitätsberechnungen wurden ebenfalls für die Kollimatormaterialien Blei und Titan durchgeführt. Während eines Jahres werden im Titankollimator 17 MBq an langlebigen Aktivierungsprodukten akkumuliert und in einem Bleikollimator reichern sich 65 MBq an (bei einer Energie von 200 MeV und einem Strahlstrom von 2 nA). Der radiologische Effekt dieser akkumulierten Aktivitäten ist relativ gering

Das Hsc/Hsp70 Co-Chaperon-Netzwerk kontrolliert die Antigenaggregation und -präsentation während der Immunzellreifung

Während der Reifung von murinen Makrophagen und BMDCs (bone marrow derived dendritic cells) akkumulieren transient ubiquitinierte Proteine in DALIS (Dendritic Cell Aggresome-Like Induced Structures). DALIS beinhalten defekte ribosomale Proteine (DRiPs - defective ribosomal products), die prozessiert und auf MHCI-Molekülen präsentiert werden. Dadurch werden cytotoxische T-Zellen (CTLs - cytotoxic T-lymphocytes) aktiviert und eine Immunantwort eingeleitet. In vorliegender Arbeit wurde am Beispiel der Formation von DALIS untersucht, wie die Aggregat-Bildung in eukaryotische Zellen durch Modulation der Proteostase- Maschinerie beeinflusst wird. Tatsächlich konnte das Chaperon/Co-Chaperon- Netzwerk als Regulator der Bildung und des Abbaus von DALIS identifiziert werden. Co-Chaperone modulieren die Interaktion zwischen Hsc/Hsp70 und dem Ubiquitin/Proteasomsystem, bzw. dem autophagischen Abbau. Die Chaperon-assoziierte Ubiquitinligase CHIP und das Ubiquitin-ähnliche Protein BAG-1 werden essentiell für die Bildung von DALIS in murinen Makrophagen und BMDCs benötigt. DesWeiteren kooperiert CHIP mit dem Autophagie-assoziierten Co-Chaperon BAG-3 und dem Ubiquitin-Adapter p62 und vermittelt den Abbau von DALIS über Chaperon-vermittelte selektive Autophagie (CASA - chaperone-assisted selective autophagy). Das Co-Chaperon HspBP1 inhibiert CHIP-Aktivität und drosselt auf diese Weise die Einschleusung von Peptiden in den Weg der Antigenprozessierung. Durch die Regulation der DALIS-Formation kontrollieren die Co-Chaperone die Präsentation von endogenen und viralen Antigenen auf MHCI-Molekülen in murinen BMDCs. In vorliegender In vorliegender Arbeit konnte zum ersten Mal gezeigt werden, dass das Chaperon/ Co-Chaperon-Netzwerk die transienten Protein-Aggregation in professionellen Antigen-präsentierenden Zellen (APC - antigen presenting cell) kontrolliert und auf dieseWeise die Immunantwort reguliert. Ähnliche Mechanismen könnten auch bei der Formation von Aggresomen oder Aggresomen-ähnlichen Aggregaten in Nicht-Immunzellen eine Rolle spielen

Development of an Enzyme-Linked Immunosorbent Assay (ELISA) for the Quantification of ARID1A in Tissue Lysates

ARID1A is a subunit of the mammalian SWI/SNF complex, which is thought to regulate gene expression through restructuring chromatin structures. Its gene ARID1A is frequently mutated and ARID1A levels are lowered in several human cancers, especially gynecologic ones. A functional ARID1A loss may have prognostic or predictive value in terms of therapeutic strategies but has not been proposed based on a quantitative method. Hardly any literature is available on ARID1A levels in tumor samples. We developed an indirect enzyme-linked immunosorbent assay (ELISA) for ARID1A based on the current EMA and FDA criteria. We demonstrated that our ELISA provides the objective, accurate, and precise quantification of ARID1A concentrations in recombinant protein solutions, cell culture standards, and tissue lysates of tumors. A standard curve analysis yielded a ‘goodness of fit’ of R2 = 0.99. Standards measured on several plates and days achieved an inter-assay accuracy of 90.26% and an inter-assay precision with a coefficient of variation of 4.53%. When tumor lysates were prepared and measured multiple times, our method had an inter-assay precision with a coefficient of variation of 11.78%. We believe that our suggested method ensures a high reproducibility and can be used for a high sample throughput to determine the ARID1A concentration in different tumor entities. The application of our ELISA on various tumor and control tissues will allow us to explore whether quantitative ARID1A measurements in tumor samples are of predictive value

Intracranial Intracerebral Schwannoma: a Case Report and Review of the Literature

Intracranial schwannomas are relatively uncommon, accounting for approximately 8% of all intracranial tumors, while intracerebral schwannomas represent an even rarer entity, responsible for roughly 1% of all intracranial schwannomas. After reviewing the relevant literature, we discussed the clinical journey of a 74-year-old woman who presented with a 3-week history of dizziness and nausea. Magnetic resonance imaging revealed a right temporal mass lesion with perifocal edema. The initial suspicion was the diagnosis of a glioblastoma or metastasis, prompting surgical intervention. During the surgery, a gross total resection of a noninvasive tumor was successfully performed. The patient’s postoperative recovery was uneventful. Histopathological examination and confrmatory immunohistochemistry played a crucial role in reaching the fnal diagnosis of an intracerebral temporal schwannoma, highlighting the diagnostic challenges posed by radiologically indistinguishable features from metastasis and gliomas. Despite these challenges, complete surgical removal remains the most preferred treatment option, resulting in a favorable long-term prognosis without the need for adjuvant or neoadjuvant chemotherapy. Intracerebral schwannomas are exceedingly rare brain tumors, often found on the brain’s surface or adjacent ventricles. Early and accurate diagnosis can be challenging due to radiological features overlapping with other intracranial pathologies. Nonetheless, histopathological examination and immunohistochemistry remain indispensable tools in establishing a defnitive diagnosis and guiding efective treatment strategies. With complete surgical excision, patients with intracerebral schwannomas can expect a positive outcome and a promising long-term prognosis. Further research and case studies are warranted to enhance our understanding of these rare tumors and improve patient outcomes

Bisulfite profiling of the MGMT promoter and comparison with routine testing in glioblastoma diagnostics

Background: Promoter methylation of the DNA repair gene O6 -methylguanine-DNA methyltransferase (MGMT) is an acknowledged predictive epigenetic marker in glioblastoma multiforme and anaplastic astrocytoma. Patients with methylated CpGs in the MGMT promoter beneft from treatment with alkylating agents, such as temozolomide, and show an improved overall survival and progression-free interval. A precise determination of MGMT promoter methyla‑ tion is of importance for diagnostic decisions. We experienced that diferent methods show partially divergent results in a daily routine. For an integrated neuropathological diagnosis of malignant gliomas, we therefore currently apply a combination of methylation-specifc PCR assays and pyrosequencing. Results: To better rationalize the variation across assays, we compared these standard techniques and assays to deep bisulfte sequencing results in a cohort of 80 malignant astrocytomas. Our deep analysis covers 49 CpG sites of the expanded MGMT promoter, including exon 1, parts of intron 1 and a region upstream of the transcription start site (TSS). We observed that deep sequencing data are in general in agreement with CpG-specifc pyrosequencing, while the most widely used MSP assays published by Esteller et al. (N Engl J Med 343(19):1350–1354, 2000. https://doi.org/ 10.1056/NEJM200011093431901) and Felsberg et al. (Clin Cancer Res 15(21):6683–6693, 2009. https://doi.org/10.1158/ 1078-0432.CCR-08-2801) resulted in partially discordant results in 22 tumors (27.5%). Local deep bisulfte sequencing (LDBS) revealed that CpGs located in exon 1 are suited best to discriminate methylated from unmethylated samples. Based on LDBS data, we propose an optimized MSP primer pair with 83% and 85% concordance to pyrosequencing and LDBS data. A hitherto neglected region upstream of the TSS, with an overall higher methylation compared to exon 1 and intron 1 of MGMT, is also able to discriminate the methylation status. Conclusion: Our integrated analysis allows to evaluate and redefne co-methylation domains within the MGMT pro‑ moter and to rationalize the practical impact on assays used in daily routine diagnostics

The Hsc/Hsp70 Co-Chaperone Network Controls Antigen Aggregation and Presentation during Maturation of Professional Antigen Presenting Cells

The maturation of mouse macrophages and dendritic cells involves the transient deposition of ubiquitylated proteins in the form of dendritic cell aggresome-like induced structures (DALIS). Transient DALIS formation was used here as a paradigm to study how mammalian cells influence the formation and disassembly of protein aggregates through alterations of their proteostasis machinery. Co-chaperones that modulate the interplay of Hsc70 and Hsp70 with the ubiquitin-proteasome system (UPS) and the autophagosome-lysosome pathway emerged as key regulators of this process. The chaperone-associated ubiquitin ligase CHIP and the ubiquitin-domain protein BAG-1 are essential for DALIS formation in mouse macrophages and bone-marrow derived dendritic cells (BMDCs). CHIP also cooperates with BAG-3 and the autophagic ubiquitin adaptor p62 in the clearance of DALIS through chaperone-assisted selective autophagy (CASA). On the other hand, the co-chaperone HspBP1 inhibits the activity of CHIP and thereby attenuates antigen sequestration. Through a modulation of DALIS formation CHIP, BAG-1 and HspBP1 alter MHC class I mediated antigen presentation in mouse BMDCs. Our data show that the Hsc/Hsp70 co-chaperone network controls transient protein aggregation during maturation of professional antigen presenting cells and in this way regulates the immune response. Similar mechanisms may modulate the formation of aggresomes and aggresome-like induced structures (ALIS) in other mammalian cell types

Nuclear data for medical applications: An overview of present status and future needs

A brief overview of nuclear data required for medical applications is given. The major emphasis is on radionuclides for internal applications, both for diagnosis and therapy. The status of the presently available data is discussed and some of the emerging needs are outlined. Most of the needs are associated with the development of non-standard positron emitters and novel therapeutic radionuclides. Some new developments in application of radionuclides, e.g. theranostic approach, multimode imaging, radionanoparticles, etc. are described and the related nuclear data needs are discussed. The possible use of newer irradiation technologies for medical radionuclide production, e.g. intermediate energy charged-particle accelerators, high-power electron accelerators for photon production, and spallation neutron sources, will place heavy demands on nuclear data

Specificity in the actions of the UBR1 ubiquitin ligase in the degradation of nuclear receptors☆

The UBR1 ubiquitin ligase promotes degradation of proteins via the N-end rule and by another mechanism that detects a misfolded conformation. Although UBR1 was shown recently to act on protein kinases whose misfolding was promoted by inhibition of Hsp90, it was unknown whether this ubiquitin ligase targeted other client types of the chaperone. We analyzed the role of UBR1 in the degradation of nuclear receptors that are classical clients of Hsp90. Our results showed that UBR1 deletion results in impaired degradation of the glucocorticoid receptor and the androgen receptor but not the estrogen receptor α. These findings demonstrate specificity in the actions of the UBR1 ubiquitin ligase in the degradation of Hsp90 clients in the presence of small molecule inhibitors that promote client misfolding

Molecular communication: An acid tale of prion formation

Some bacteria use lactic acid to communicate with yeast cells

The C-terminus of MIP-T3 protein is required for ubiquitin-proteasome-mediated degradation in human cells.

The intraflagellar transport (IFT) complex is essential for the formation and functional maintenance of eukaryotic cilia which play a vital role in development and tissue homeostasis. However, the biochemical characteristics and precise functions of IFT proteins remain unknown. Here, we report that MIP-T3, a human microtubule-interacting protein recently identified as a novel conserved component of the IFT complex, is an easily degradable protein in human cell lines. Protein degradation is mediated by the ubiquitin-proteasome system, and the C-terminus is required for ubiquitination and proteasome-mediated degradation of MIP-T3 protein. This study provides the first evidence for regulation of IFT protein stability