TY - JOUR
A1 - Weich, Alexander
A1 - Werner, Rudolf A.
A1 - Buck, Andreas K.
A1 - Hartrampf, Philipp E.
A1 - Serfling, Sebastian E.
A1 - Scheurlen, Michael
A1 - Wester, Hans-Jürgen
A1 - Meining, Alexander
A1 - Kircher, Stefan
A1 - Higuchi, Takahiro
A1 - Pomper, Martin G.
A1 - Rowe, Steven P.
A1 - Lapa, Constantin
A1 - Kircher, Malte
T1 - CXCR4-Directed PET/CT in Patients with Newly Diagnosed Neuroendocrine Carcinomas
JF - Diagnostics
N2 - We aimed to elucidate the diagnostic potential of the C-X-C motif chemokine receptor 4 (CXCR4)-directed positron emission tomography (PET) tracer \(^{68}\)Ga-Pentixafor in patients with poorly differentiated neuroendocrine carcinomas (NEC), relative to the established reference standard \(^{18}\)F-FDG PET/computed tomography (CT). In our database, we retrospectively identified 11 treatment-naïve patients with histologically proven NEC, who underwent \(^{18}\)F-FDG and CXCR4-directed PET/CT for staging and therapy planning. The images were analyzed on a per-patient and per-lesion basis and compared to immunohistochemical staining (IHC) of CXCR4 from PET-guided biopsies. \(^{68}\)Ga-Pentixafor visualized tumor lesions in 10/11 subjects, while \(^{18}\)F-FDG revealed sites of disease in all 11 patients. Although weak to moderate CXCR4 expression could be corroborated by IHC in 10/11 cases, \(^{18}\)F-FDG PET/CT detected significantly more tumor lesions (102 vs. 42; total lesions, n = 107; p < 0.001). Semi-quantitative analysis revealed markedly higher 18F-FDG uptake as compared to \(^{68}\)Ga-Pentixafor (maximum and mean standardized uptake values (SUV) and tumor-to-background ratios (TBR) of cancerous lesions, SUVmax: 12.8 ± 9.8 vs. 5.2 ± 3.7; SUVmean: 7.4 ± 5.4 vs. 3.1 ± 3.2, p < 0.001; and, TBR 7.2 ± 7.9 vs. 3.4 ± 3.0, p < 0.001). Non-invasive imaging of CXCR4 expression in NEC is inferior to the reference standard \(^{18}\)F-FDG PET/CT.
KW - CXCR4
KW - NET
KW - NEC
KW - 68Ga-Pentixafor
KW - 18F-FDG
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-234231
SN - 2075-4418
VL - 11
IS - 4
ER -
TY - JOUR
A1 - Mönius, Katja
T1 - Eigenvalues of zero-divisor graphs of finite commutative rings
JF - Journal of Algebraic Combinatorics
N2 - We investigate eigenvalues of the zero-divisor graph Γ(R) of finite commutative rings R and study the interplay between these eigenvalues, the ring-theoretic properties of R and the graph-theoretic properties of Γ(R). The graph Γ(R) is defined as the graph with vertex set consisting of all nonzero zero-divisors of R and adjacent vertices x, y whenever xy=0. We provide formulas for the nullity of Γ(R), i.e., the multiplicity of the eigenvalue 0 of Γ(R). Moreover, we precisely determine the spectra of \(\Gamma ({\mathbb {Z}}_p \times {\mathbb {Z}}_p \times {\mathbb {Z}}_p)\) and \(\Gamma ({\mathbb {Z}}_p \times {\mathbb {Z}}_p \times {\mathbb {Z}}_p \times {\mathbb {Z}}_p)\) for a prime number p. We introduce a graph product ×Γ with the property that Γ(R)≅Γ(R\(_1\))×Γ⋯×ΓΓ(R\(_r\)) whenever R≅R\(_1\)×⋯×R\(_r\). With this product, we find relations between the number of vertices of the zero-divisor graph Γ(R), the compressed zero-divisor graph, the structure of the ring R and the eigenvalues of Γ(R).
KW - EJMA-D-19-00287
KW - Zero-divisor graphs
KW - Graph eigenvalues
KW - Graphnullity
KW - Graph products
KW - Local rings
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-232792
SN - 0925-9899
VL - 54
ER -
TY - JOUR
A1 - Grob, Robin
A1 - Tritscher, Clara
A1 - Grübel, Kornelia
A1 - Stigloher, Christian
A1 - Groh, Claudia
A1 - Fleischmann, Pauline N.
A1 - Rössler, Wolfgang
T1 - Johnston's organ and its central projections in Cataglyphis desert ants
JF - Journal of Comparative Neurology
N2 - The Johnston's organ (JO) in the insect antenna is a multisensory organ involved in several navigational tasks including wind‐compass orientation, flight control, graviception, and, possibly, magnetoreception. Here we investigate the three dimensional anatomy of the JO and its neuronal projections into the brain of the desert ant Cataglyphis, a marvelous long‐distance navigator. The JO of C. nodus workers consists of 40 scolopidia comprising three sensory neurons each. The numbers of scolopidia slightly vary between different sexes (female/male) and castes (worker/queen). Individual scolopidia attach to the intersegmental membrane between pedicel and flagellum of the antenna and line up in a ring‐like organization. Three JO nerves project along the two antennal nerve branches into the brain. Anterograde double staining of the antennal afferents revealed that JO receptor neurons project to several distinct neuropils in the central brain. The T5 tract projects into the antennal mechanosensory and motor center (AMMC), while the T6 tract bypasses the AMMC via the saddle and forms collaterals terminating in the posterior slope (PS) (T6I), the ventral complex (T6II), and the ventrolateral protocerebrum (T6III). Double labeling of JO and ocellar afferents revealed that input from the JO and visual information from the ocelli converge in tight apposition in the PS. The general JO anatomy and its central projection patterns resemble situations in honeybees and Drosophila. The multisensory nature of the JO together with its projections to multisensory neuropils in the ant brain likely serves synchronization and calibration of different sensory modalities during the ontogeny of navigation in Cataglyphis.
KW - ant brain
KW - chordotonal organ
KW - graviception
KW - magnetic compass
KW - multisensory integration
KW - navigation
KW - wind compass
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225679
VL - 529
IS - 8
SP - 2138
EP - 2155
ER -
TY - JOUR
A1 - Full, Julian
A1 - Panchal, Santosh P.
A1 - Götz, Julian
A1 - Krause, Ana‐Maria
A1 - Nowak‐Król, Agnieszka
T1 - Modular Synthesis of Organoboron Helically Chiral Compounds: Cutouts from Extended Helices
JF - Angewandte Chemie International Edition
N2 - Two types of helically chiral compounds bearing one and two boron atoms were synthesized by a modular approach. Formation of the helical scaffolds was executed by the introduction of boron to flexible biaryl and triaryl derived from small achiral building blocks. All‐ortho‐fused azabora[7]helicenes feature exceptional configurational stability, blue or green fluorescence with quantum yields (Φ\(_{fl}\)) of 18–24 % in solution, green or yellow solid‐state emission (Φ\(_{fl}\) up to 23 %), and strong chiroptical response with large dissymmetry factors of up to 1.12×10\(^{-2}\). Azabora[9]helicenes consisting of angularly and linearly fused rings are blue emitters exhibiting Φ\(_{fl}\) of up to 47 % in CH\(_{2}\)Cl\(_{2}\) and 25 % in the solid state. As revealed by the DFT calculations, their P–M interconversion pathway is more complex than that of H1. Single‐crystal X‐ray analysis shows clear differences in the packing arrangement of methyl and phenyl derivatives. These molecules are proposed as primary structures of extended helices.
KW - chirality
KW - circular dichroism
KW - fluorescence
KW - helicene
KW - organoboron
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225775
VL - 60
IS - 8
SP - 4350
EP - 4357
ER -
TY - JOUR
A1 - Urlaub, Jonas
A1 - Kaiser, Reinhard P.
A1 - Scherf‐Clavel, Oliver
A1 - Bolm, Carsten
A1 - Holzgrabe, Ulrike
T1 - Investigation of isomerization of dexibuprofen in a ball mill using chiral capillary electrophoresis
JF - Electrophoresis
N2 - Besides the racemate, the S‐enantiomer of ibuprofen (Ibu) is used for the treatment of inflammation and pain. Since the configurational stability of S‐Ibu in solid state is of interest, it was studied by means of ball milling experiments. For the evaluation of the enantiomeric composition, a chiral CE method was developed and validated according to the ICH guideline Q2(R1). The addition of Mg\(^{2+}\), Ca\(^{2+}\), or Zn\(^{2+}\) ions to the background electrolyte (BGE) was found to improve Ibu enantioresolution. Chiral separation of Ibu enantiomers was achieved on a 60.2 cm (50.0 cm effective length) x 75 μm fused‐silica capillary using a background electrolyte (BGE) composed of 50 mM sodium acetate, 10 mM magnesium acetate tetrahydrate, and 35 mM heptakis‐(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin (TM‐β‐CD) as chiral selector. The quantification of R‐Ibu in the mixture was performed using the normalization procedure. Linearity was evaluated in the range of 0.68–5.49% R‐Ibu (R\(^{2}\) = 0.999), recovery was found to range between 97 and 103%, the RSD of intra‐ and interday precision below 2.5%, and the limit of quantification for R‐ in S‐Ibu was calculated to be 0.21% (extrapolated) and 0.15% (dilution of racemic ibuprofen), respectively. Isomerization of S‐Ibu was observed under basic conditions by applying long milling times and high milling frequencies.
KW - capillary electrophoresis
KW - chiral separation
KW - Ibuprofen
KW - isomerization
KW - validation
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225852
VL - 42
IS - 17-18
SP - 1790
EP - 1799
ER -
TY - JOUR
A1 - Zahoranová, Anna
A1 - Luxenhofer, Robert
T1 - Poly(2‐oxazoline)‐ and Poly(2‐oxazine)‐Based Self‐Assemblies, Polyplexes, and Drug Nanoformulations—An Update
JF - Advanced Healthcare Materials
N2 - For many decades, poly(2‐oxazoline)s and poly(2‐oxazine)s, two closely related families of polymers, have led the life of a rather obscure research topic with only a few research groups world‐wide working with them. This has changed in the last five to ten years, presumably triggered significantly by very promising clinical trials of the first poly(2‐oxazoline)‐based drug conjugate. The huge chemical and structural toolbox poly(2‐oxazoline)s and poly(2‐oxazine)s has been extended very significantly in the last few years, but their potential still remains largely untapped. Here, specifically, the developments in macromolecular self‐assemblies and non‐covalent drug delivery systems such as polyplexes and drug nanoformulations based on poly(2‐oxazoline)s and poly(2‐oxazine)s are reviewed. This highly dynamic field benefits particularly from the extensive synthetic toolbox poly(2‐oxazoline)s and poly(2‐oxazine)s offer and also may have the largest potential for a further development. It is expected that the research dynamics will remain high in the next few years, particularly as more about the safety and therapeutic potential of poly(2‐oxazoline)s and poly(2‐oxazine)s is learned.
KW - block copolymers
KW - colloids
KW - cytotoxicity
KW - drug delivery
KW - micelles
KW - microphase separation
KW - thermogelling
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225833
VL - 10
IS - 6
ER -
TY - JOUR
A1 - Hojsgaard, Diego
A1 - Schartl, Manfred
T1 - Skipping sex: A nonrecombinant genomic assemblage of complementary reproductive modules
JF - BioEssays
N2 - The unusual occurrence and developmental diversity of asexual eukaryotes remain a puzzle. De novo formation of a functioning asexual genome requires a unique assembly of sets of genes or gene states to disrupt cellular mechanisms of meiosis and gametogenesis, and to affect discrete components of sexuality and produce clonal or hemiclonal offspring. We highlight two usually overlooked but essential conditions to understand the molecular nature of clonal organisms, that is, a nonrecombinant genomic assemblage retaining modifiers of the sexual program, and a complementation between altered reproductive components. These subtle conditions are the basis for physiologically viable and genetically balanced transitions between generations. Genomic and developmental evidence from asexual animals and plants indicates the lack of complementation of molecular changes in the sexual reproductive program is likely the main cause of asexuals' rarity, and can provide an explanatory frame for the developmental diversity and lability of developmental patterns in some asexuals as well as for the discordant time to extinction estimations.
KW - amphimixis
KW - apomixis
KW - automixis
KW - gynogenesis
KW - hybridogenesis
KW - parthenogenesis
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225818
VL - 43
IS - 1
ER -
TY - JOUR
A1 - Budiman, Yudha P.
A1 - Westcott, Stephen A.
A1 - Radius, Udo
A1 - Marder, Todd B.
T1 - Fluorinated Aryl Boronates as Building Blocks in Organic Synthesis
JF - Advanced Synthesis & Catalysis
N2 - Organoboron compounds are well known building blocks for many organic reactions. However, under basic conditions, polyfluorinated aryl boronic acid derivatives suffer from instability issues that are accelerated in compounds containing an ortho‐fluorine group, which result in the formation of the corresponding protodeboronation products. Therefore, a considerable amount of research has focused on novel methodologies to synthesize these valuable compounds while avoiding the protodeboronation issue. This review summarizes the latest developments in the synthesis of fluorinated aryl boronic acid derivatives and their applications in cross‐coupling reactions and other transformations.
image
KW - homogeneous catalysis
KW - boron reagents
KW - boronates
KW - fluorine
KW - fluoroarene
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225908
VL - 363
IS - 9
SP - 2224
EP - 2255
ER -
TY - JOUR
A1 - Ravat, Prince
T1 - Carbo[n]helicenes Restricted to Enantiomerize: An Insight into the Design Process of Configurationally Stable Functional Chiral PAHs
JF - Chemistry – A European Journal
N2 - The most important stereodynamic feature of carbo[n]helicenes is the interconversion of their enantiomers. The Gibbs activation energy (ΔG≠(T)) of this process, which determines the rate of enantiomerization, dictates the configurational stability of [n]helicenes. High values of ΔG≠(T) are required for applications of functional chiral molecules incorporating [n]helicenes or helicene substructures. This minireview provides an overview of the mechanism, recent developments, and factors affecting the enantiomerization of [n]helicenes, which will accelerate the design process of configurationally stable functional chiral molecules based on helicene substructures. Additionally, this minireview addresses the misconception and irregularities in the recent literature on how the terms “racemization” and “enantiomerization” are used as well as how the activation parameters are calculated for [n]helicenes and related compounds.
KW - [n]helicenes
KW - configurational stability
KW - enantiomerization
KW - Gibbs activation energy
KW - racemization
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225871
VL - 27
IS - 12
SP - 3957
EP - 3967
ER -
TY - JOUR
A1 - Sprenger, Philipp P.
A1 - Müsse, Christian
A1 - Hartke, Juliane
A1 - Feldmeyer, Barbara
A1 - Schmitt, Thomas
A1 - Gebauer, Gerhard
A1 - Menzel, Florian
T1 - Dinner with the roommates: trophic niche differentiation and competition in a mutualistic ant‐ant association
JF - Ecological Entomology
N2 - 1. The potential for competition is highest among species in close association. Despite net benefits for both parties, mutualisms can involve costs, including food competition. This might be true for the two neotropical ants Camponotus femoratus and Crematogaster levior, which share the same nest in a presumably mutualistic association (parabiosis).
2. While each nest involves one Crematogaster and one Camponotus partner, both taxa were recently found to comprise two cryptic species that show no partner preferences and seem ecologically similar. Since these cryptic species often occur in close sympatry, they might need to partition their niches to avoid competitive exclusion.
3. Here, we investigated first, is there interference competition between parabiotic Camponotus and Crematogaster, and do they prefer different food sources under competition? And second, is there trophic niche partitioning between the cryptic species of either genus?
4. Using cafeteria experiments, neutral lipid fatty acid and stable isotope analyses, we found evidence for interference competition, but also trophic niche partitioning between Camponotus and Crematogaster. Both preferred protein‐ and carbohydrate‐rich baits, but at protein‐rich baits Ca. femoratus displaced Cr. levior over time, suggesting a potential discovery‐dominance trade‐off between parabiotic partners. Only limited evidence was found for trophic differentiation between the cryptic species of each genus.
5. Although we cannot exclude differentiation in other niche dimensions, we argue that neutral dynamics might mediate the coexistence of cryptic species. This model system is highly suitable for further studies of the maintenance of species diversity and the role of mutualisms in promoting species coexistence.
KW - Cryptic species
KW - Formicidae
KW - neutral theory
KW - niche partitioning
KW - nutrition
KW - parabiosis
KW - species coexistence mechanism
KW - trade‐offs
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228215
VL - 46
IS - 3
SP - 562
EP - 572
ER -