Insect Adhesion Secretions: Similarities and Dissimilarities in Hydrocarbon Profiles of Tarsi and Corresponding Tibiae

Spatially controlled in vivo sampling by contact solid phase microextraction with a non-coated silica fiber combined with gas chromatography-mass spectrometry (GC-MS) was utilized for hydrocarbon profiling in tarsal adhesion secretions of four insect species (Nicrophorus vespilloides, Nicrophorus nepalensis, Sagra femorata, and Gromphadorhina portentosa) by using distinct adhesion systems, viz. hairy or smooth tarsi. For comparison, corresponding samples from tibiae, representing the general cuticular hydrocarbon profile, were analyzed to enable the statistical inference of active molecular adhesion principles in tarsal secretions possibly contributed by specific hydrocarbons. n-Alkanes, monomethyl and dimethyl alkanes, alkenes, alkadienes, and one aldehyde were detected. Multivariate statistical analysis (principal component and orthogonal partial least square discriminant analyses) gave insights into distinctive molecular features among the various insect species and between tarsus and tibia samples. In general, corresponding hydrocarbon profiles in tarsus and tibia samples largely resembled each other, both qualitatively and in relative abundances as well. However, several specific hydrocarbons showed significantly different relative abundances between corresponding tarsus and tibia samples, thus indicating that such differences of specific hydrocarbons in the complex mixtures might constitute a delicate mechanism for fine-tuning the reversible attachment performances in tarsal adhesive fluids that are composed of substances originating from the same pool as cuticular hydrocarbons. Caused by melting point depression, the multicomponent tarsal adhesion secretion, made up of straight chain alkanes, methyl alkanes, and alkenes will have a semi-solid, grease-like consistency, which might provide the basis for a good reversible attachment performance.     

Long-Term Effects of Neural Precursor Cell Transplantation on Secondary Injury Processes and Functional Recovery after Severe Cervical Contusion-Compression Spinal Cord Injury

Cervical spinal cord injury (SCI) remains a devastating event without adequate treatment options despite decades of research. In this context, the usefulness of common preclinical SCI models has been criticized. We, therefore, aimed to use a clinically relevant animal model of severe cervical SCI to assess the long-term effects of neural precursor cell (NPC) transplantation on secondary injury processes and functional recovery. To this end, we performed a clip contusion-compression injury at the C6 level in 40 female Wistar rats and a sham surgery in 10 female Wistar rats. NPCs, isolated from the subventricular zone of green fluorescent protein (GFP) expressing transgenic rat embryos, were transplanted ten days after the injury. Functional recovery was assessed weekly, and FluoroGold (FG) retrograde fiber-labeling, as well as manganese-enhanced magnetic resonance imaging (MEMRI), were performed prior to the sacrifice of the animals eight weeks after SCI. After cryosectioning of the spinal cords, immunofluorescence staining was conducted. Results were compared between the treatment groups (NPC, Vehicle, Sham) and statistically analyzed (p < 0.05 was considered significant). Despite the severity of the injury, leading to substantial morbidity and mortality during the experiment, long-term survival of the engrafted NPCs with a predominant differentiation into oligodendrocytes could be observed after eight weeks. While myelination of the injured spinal cord was not significantly improved, NPC treated animals showed a significant increase of intact perilesional motor neurons and preserved spinal tracts compared to untreated Vehicle animals. These findings were associated with enhanced preservation of intact spinal cord tissue. However, reactive astrogliosis and inflammation where not significantly reduced by the NPC-treatment. While differences in the Basso–Beattie–Bresnahan (BBB) score and the Gridwalk test remained insignificant, animals in the NPC group performed significantly better in the more objective CatWalk XT gait analysis, suggesting some beneficial effects of the engrafted NPCs on the functional recovery after severe cervical SCI.     

The Absence of Extracellular Cold-Inducible RNA-Binding Protein (eCIRP) Promotes Pro-Angiogenic Microenvironmental Conditions and Angiogenesis in Muscle Tissue Ischemia

Extracellular Cold-inducible RNA-binding protein (eCIRP), a damage-associated molecular pattern, is released from cells upon hypoxia and cold-stress. The overall absence of extra- and intracellular CIRP is associated with increased angiogenesis, most likely induced through influencing leukocyte accumulation. The aim of the present study was to specifically characterize the role of eCIRP in ischemia-induced angiogenesis together with the associated leukocyte recruitment. For analyzing eCIRPs impact, we induced muscle ischemia via femoral artery ligation (FAL) in mice in the presence or absence of an anti-CIRP antibody and isolated the gastrocnemius muscle for immunohistological analyses. Upon eCIRP-depletion, mice showed increased capillary/muscle fiber ratio and numbers of proliferating endothelial cells (CD31⁺/CD45⁻/BrdU⁺). This was accompanied by a reduction of total leukocyte count (CD45⁺), neutrophils (MPO⁺), neutrophil extracellular traps (NETs) (MPO⁺CitH3⁺), apoptotic area (ascertained via TUNEL assay), and pro-inflammatory M1-like polarized macrophages (CD68⁺/MRC1⁻) in ischemic muscle tissue. Conversely, the number of regenerative M2-like polarized macrophages (CD68⁺/MRC1⁺) was elevated. Altogether, we observed that eCIRP depletion similarly affected angiogenesis and leukocyte recruitment as described for the overall absence of CIRP. Thus, we propose that eCIRP is mainly responsible for modulating angiogenesis via promoting pro-angiogenic microenvironmental conditions in muscle ischemia.     

Hybrid Chemoenzymatic Synthesis of C7-Sugars for Molecular Evidence of in vivo Shikimate Pathway Inhibition

The design of distinctive chemical synthesis strategies aims for the most efficient routes towards versatile compounds in drug target studies. Here, we establish a powerful hybrid synthetic approach of total chemical and chemoenzymatic synthesis to efficiently obtain various 7-deoxy-sedoheptulose (7dSh, 1 ) analogues, unique C₇ sugars, for structure-activity relationship studies. 7dSh ( 1 ) is a rare microbial sugar with in planta herbicidal activity. As natural antimetabolite of 3-dehydroquinate synthase (DHQS), 7dSh ( 1 ) inhibits the shikimate pathway, which is essential for the synthesis of aromatic amino acids in bacteria, fungi, and plants, but absent in mammals. As glyphosate, the most used chemical herbicide faces restrictions worldwide, DHQS has gained more attention as valid target of herbicides and antimicrobial agents. In vitro and in vivo analyses of the C₇-deoxysugars confirm DHQS as enzymatic target, highlight the crucial role of uptake for inhibition and add molecular aspects to target mechanism studies of C₇-sugars as our contribution to global efforts for alternative weed-control strategies.     

Hexafluoroisopropyl Carbamates as Selective MAGL and Dual MAGL/FAAH Inhibitors: Biochemical and Physicochemical Properties

A series of hexafluoroisopropyl carbamates with indolylalkyl- and azaindolylalkyl-substituents at the carbamate nitrogen was synthesized and evaluated for inhibition of the endocannabinoid degrading enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). The synthesized derivatives with butyl to heptyl spacers between the heteroaryl and the carbamate moiety were inhibitors of both enzymes. For investigated compounds in which the alkyl chain was partially incorporated into a piperidine ring, different results were obtained. Compounds with a methylene spacer between the piperidine ring and the heteroaromatic system were found to be selective MAGL inhibitors, while an extension of the alkyl spacer to two to four atoms resulted in dual inhibition of FAAH/MAGL. The only small change in enzyme inhibitory activity with variation of the heteroaromatic system indicates that the reactive hexafluoroisopropyl carbamate group is mainly responsible for the strength of the inhibitory effect of the compounds. Selected derivatives were also tested for hydrolytic stability in aqueous solution, liver homogenate and blood plasma as well as for aqueous solubility and for permeability in a Caco-2 cell model. Some compounds showed a slightly higher MAGL inhibitory effect than the known selective MAGL inhibitor ABX-1431 and also partly surpassed this substance with regard to certain physicochemical and biochemical properties such as water solubility and cell permeability.     

In situ anisotropic NiO nanostructure growth at high temperature and under water vapor

Anisotropic growth of nanostructures from individual nickel nanoparticles was observed during in situ heating experiments in an environmental scanning electron microscope (ESEM) at 800°C under water vapor atmosphere. The morphology of nanostructures exhibited one directional growth with rates ranging below 1.8 nm/s. Energy dispersive X-ray spectroscopy and selected area electron diffraction confirmed NiO stoichiometry of the growing nanostructures. Variations of the oxygen partial pressure during ex situ annealing and in situ ESEM heating experiments elucidate that anisotropic NiO growth is energetically favored in areas where the local surface energy density is relatively high. Growth of NiO nanostructures was absent in dry air and dry nitrogen environments and required the presence of water vapor. The results of this study suggest that the manipulation of surface energy prior to exposure to water vapor at elevated temperatures can prevent unwanted oxide nanostructure growth.     

GABAA Receptor Autoantibodies Decrease GABAergic Synaptic Transmission in the Hippocampal CA3 Network

Autoimmune encephalitis associated with antibodies (Abs) against α1, β3, and γ2 subunits of γ-aminobutyric acid receptor A (GABA_AR) represents a severe form of encephalitis with refractory seizures and status epilepticus. Reduction in inhibitory GABAergic synaptic activity is linked to dysfunction of neuronal networks, hyperexcitability, and seizures. The aim in this study was to investigate the direct pathogenic effect of a recombinant GABA_AR autoantibody (rAb-IP2), derived from the cerebrospinal fluid (CSF) of a patient with autoimmune GABA_AR encephalitis, on hippocampal CA1 and CA3 networks. Acute brain slices from C57BL/6 mice were incubated with rAb-IP2. The spontaneous synaptic GABAergic transmission was measured using electrophysiological recordings in voltage-clamp mode. The GABA_AR autoantibody rAb-IP2 reduced inhibitory postsynaptic signaling in the hippocampal CA1 pyramidal neurons with regard to the number of spontaneous inhibitory postsynaptic currents (sIPSCs) but did not affect their amplitude. In the hippocampal CA3 network, decreased number and amplitude of sIPSCs were detected, leading to decreased GABAergic synaptic transmission. Immunohistochemical staining confirmed the rAb-IP2 bound to hippocampal tissue. These findings suggest that GABA_AR autoantibodies exert direct functional effects on both hippocampal CA1 and CA3 pyramidal neurons and play a crucial role in seizure generation in GABA_AR autoimmune encephalitis.     

Investigation of modified SEBS‐based thermoplastic elastomers by temperature scanning stress relaxation measurements

Thermoplastic elastomers (TPEs) based on poly(styrene‐b‐ethylene/butylene‐b‐styrene) (SEBS), modified with poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE), were investigated by a new testing method. The development and characterization of TPEs with improved temperature and oil resistance is a current area of research to extend the applications of TPEs, especially in the automotive industry. Thermal scanning stress relaxation (TSSR) was used to investigate the relaxation behavior of compounds containing SEBS, blended with extender oil, various amounts of PPE and in some cases with a thermoplastic polymer. Polyamide 12 (PA12) or polypropylene (PP) were used as the thermoplastic component. TSSR measurements were applied to detect relaxation changes in the glass transition region of the polystyrene blocks mixed with PPE. It was shown that the glass transition temperature increased with addition of PPE to the compound up to a limit of approximately 150°C, which corresponded to a weight fraction of PPE in the polystyrene (PS)‐block of 0.5. The increased glass transition temperature lead to SEBS‐based thermoplastic elastomer compounds with improved upper service temperatures. Phase images obtained by atomic force microscopy showed that the addition of PPE results in an increase of hard phase dimension. The addition of a thermoplastic polymer improved the mechanical properties and temperature resistance, but naturally decreased the elasticity of the compounds. Compounds containing PA12 exhibited an improved oil resistance. POLYM. ENG. SCI., 45:1498–1507, 2005. © 2005 Society of Plastics Engineers     

Structural control in radical polymerization with 1,1-diphenylethylene. Part 3. Aqueous heterophase polymerization

Results on aqueous heterophase polymerization in the presence of either 1,1-diphenylethylene or water-soluble precursor polymers containing an α,p-dimer unit of 1,1-diphenylethylene are reported. The precursor polymers are bound covalently to the particles due to a special kind of chain transfer reaction showing on the one hand some features of controlled radical polymerization and leading on the other hand to the formation of block copolymers. Moreover, the covalently bound precursor molecules act as very efficient colloidal stabilizers of the final dispersion and thus, they can be considered as reactive surfactant with the additional ability to control radical polymerization (controlsurf). Under optimum conditions the precursor polymer molecules are almost completely covalently attached to polymer particles. Results are presented regarding block copolymer yields, solids content, and particle diameter in dependence on the polymerization conditions, particularly the precursor polymer concentration, the monomer as well as the initiator concentration, and the initiator type. Under optimum conditions the attainable block copolymer yields and the solids content of the final latexes can be above 95 and about 40%, respectively. Based on experimental results the mechanism of this special kind of controlled radical polymerization under the peculiarities of aqueous heterophase polymerization is discussed.