Influence of Insulin Receptor Single Nucleotide Polymorphisms on Glycaemic Control and Formation of Anti-Insulin Antibodies in Diabetes Mellitus

Single nucleotide polymorphisms (SNPs) in insulin and insulin receptor genes may influence the interaction between the two molecules, as may anti-insulin antibodies (IAs), commonly found in patients with type 1 diabetes mellitus (T1D) or type 2 diabetes mellitus (T2D) treated with exogenous insulin. We examined the impact of two SNPs in the human insulin gene (INS), rs3842752 and rs689, and two in the insulin receptor gene (INSR) rs2245649 and rs2229429, on disease susceptibility, glycaemic control, and IAs formation in 100 T1D patients and 101 T2D patients treated with insulin. 79 individuals without diabetes were typed as healthy controls. The minor alleles of rs3842752 and rs689 in INS protected against T1D (OR: 0.50, p = 0.01 and OR: 0.44; p = 0.002, respectively). The minor alleles of both rs2245649 and rs2229429 in INSR were risk factors for poor glycaemic control (HbA1c ≥ 80 mmol/mol) in T1D (OR: 5.35, p = 0.009 and OR: 3.10, p = 0.01, respectively). Surprisingly, the minor alleles of rs2245649 and rs2229429 in INSR associated strongly with the absence of IAs in T1D (OR = 0.28, p = 0.008 and OR = 0.30, p = 0.002, respectively). In conclusion, the minor alleles of the investigated INS SNPs protect against T1D, and the minor alleles of the investigated INSR SNPs are associated with poor glycaemic control and the absence of IAs in T1D.     

In Vitro Characterization of the Physical Interactions between the Long Noncoding RNA TERRA and the Telomeric Proteins TRF1 and TRF2

RNA-protein interactions drive key cellular pathways such as protein translation, nuclear organization and genome stability maintenance. The human telomeric protein TRF2 binds to the long noncoding RNA TERRA through independent domains, including its N-terminal B domain. We previously demonstrated that TRF2 B domain binding to TERRA supports invasion of TERRA into telomeric double stranded DNA, leading to the formation of telomeric RNA:DNA hybrids. The other telomeric protein TRF1, which also binds to TERRA, suppresses this TRF2-associated activity by preventing TERRA-B domain interactions. Herein, we show that the binding of both TRF1 and TRF2 to TERRA depends on the ability of the latter to form G-quadruplex structures. Moreover, a cluster of arginines within the B domain is largely responsible for its binding to TERRA. On the other side, a patch of glutamates within the N-terminal A domain of TRF1 mainly accounts for the inhibition of TERRA-B domain complex formation. Finally, mouse TRF2 B domain binds to TERRA, similarly to its human counterpart, while mouse TRF1 A domain lacks the inhibitory activity. Our data shed further light on the complex crosstalk between telomeric proteins and RNAs and suggest a lack of functional conservation in mouse.     

Partialsynthesen von Cardenoliden und Cardenolid-Analogen. XII. Synthese 21-substituierter Cardenolide durch Oxidation von 17β - (Fur-3-yl)-Steroiden und nukleophile Substitution

Partial Syntheses of Cardenolides and Cardenolide-Analogues. XII. Synthesis of 21-Substituted Cardenolides by Oxidation of 17β - (3-Furyl)-Steroids and Nucleophilic Substitution Oxidation of 17β-(3-furyl)-5β, 14β-androstane-3β, 14β-diol 3-acetate ( 2b ) with chromic acid yielded the 14,21-epoxy-cardenolide 4 . After elimination of the 14β-hydroxy group of 2b the unsaturated furyl derivative 5 , when treated with chromic acid, gave a mixture of the diastereomeric unsaturated 21ξ-hydroxy-cardenolides 8a which were converted with N-bromoacetamide to a mixture of the 14β, 15β-epoxy-21ξ-hydroxy-cardenolides 9a . The hydroxy-cardenolides 8a and 9a were acetylated to the 21ξ-acetoxy-cardenolides 8b/8c and 9b/9c , respectively, and they reacted with primary and secondary amines to give the corresponding N-substituted 21ξ-amino-cardenolides 11a--11c and 12b , respectively. When reacted with p-toluenesulfonyl chloride both 8a and 9a yielded the 21ξ-chloro-cardenolides 11d/11e and 12c/12d , respectively, the chlorine of which could easily be substituted by S_N1- and S_N2-reactions.     

SMART RHESINs—Superparamagnetic Magnetite Architecture Made of Phenolic Resin Hollow Spheres Coated with Eu(III) Containing Silica Nanoparticles for Future Quantitative Magnetic Particle Imaging Applications

Magnetic particle imaging (MPI) is a powerful and rapidly growing tomographic imaging technique that allows for the non-invasive visualization of superparamagnetic nanoparticles (NPs) in living matter. Despite its potential for a wide range of applications, the intrinsic quantitative nature of MPI has not been fully exploited in biological environments. In this study, a novel NP architecture that overcomes this limitation by maintaining a virtually unchanged effective relaxation (Brownian plus Néel) even when immobilized is presented. This superparamagnetic magnetite architecture made of phenolic resin hollow spheres coated with Eu(III) containing silica nanoparticles (SMART RHESINs) was synthesized and studied. Magnetic particle spectroscopy (MPS) measurements confirm their suitability for potential MPI applications. Photobleaching studies show an unexpected photodynamic due to the fluorescence emission peak of the europium ion in combination with the phenol formaldehyde resin (PFR). Cell metabolic activity and proliferation behavior are not affected. Colocalization experiments reveal the distinct accumulation of SMART RHESINs near the Golgi apparatus. Overall, SMART RHESINs show superparamagnetic behavior and special luminescent properties without acute cytotoxicity, making them suitable for bimodal imaging probes for medical use like cancer diagnosis and treatment. SMART RHESINs have the potential to enable quantitative MPS and MPI measurements both in mobile and immobilized environments.     

Orthoamide. LIV [1] Beiträge zur Chemie azavinyloger Orthoamid‐Derivate der Ameisensäure

Orthoamides. LIV. Contributions to the Chemistry of Azavinylogous Orthoformic Acid Amide Derivatives The azavinylogous aminalester 3 reacts with primary amines to give amidines 5 and 6 . In the reaction of 3 with aniline the azavinylogous amidine 7 is produced additionally to the amidine 5c . Ethylendiamine is formylated at both aminogroups, the bis‐amidine 8 thus formed is transformed to the salts 9a , b . Benzoxazole and benzimidazole can be prepared from 3 and o‐aminophenol and o‐phenylenediamine, resp. carboxylic acid amides, urea, thiourea, aromatic acid hydrazides 17 and the sulfonylhydrazide 19 are formylated by 3 at nitrogen to give N‐acylated formamidines 14 , 16 , 18 , 20 . From 3 and aliphatic acid hydrazides 17 and alkylhydrazines, resp., can be obtained 1,2,4‐triazole 21 and 1‐alkyl‐1,2,4‐triazoles 22a , b , resp. N,N‐dimethylcyanacetamide ( 32 ) reacts with 3 and the orthoamide 4a , resp., to give a mixture of the formylated compound 34 and the amidine 33 . The reaction conditions are of low influence on the ratio in which 33 and 34 are formed. The orthoamide 4b and 32 react to afford a mixture of the amidine 35 and the enamine 36 . Hydrogensulfide acts on 3 giving N,N‐dimethylthioformamide ( 37 ). From 3 and 1‐alkynes 41 can be prepared the amidines 42 . Hydrolysis of 42b affords phenylpropiolaldehyde ( 43 ). The alkylation of the aminalester 3 gives rise to the formation of vinylogous amidiniumsalts 1c and 1d , resp., additionally is formed the amide acetal 2a . The salt 1d can also be prepared from 3 and borontrifluoride‐ether. Iodide reacts with N,N‐dimethylformamide acetals 12a , b in an unclear, complicated manner giving orthoesters 53 , N,N‐dimethylformamide, alkyliodides, alcohols, ammoniumiodides 46 and carbondioxide. The action of halogens on 3 affords the salts 1a , b , c , e , f depending on the chosen stoichiometric ratio. Aromatic aldehydes are suited for trapping azavinylogous carbenes formed on thermolysis of 3 — 1,3‐oxazoles 69 are the reaction products. From 3 and propionaldehyde the amidine 65 can be obtained with low yield. Carbondisulfide transforms 3 to the azavinylogous salt 66 . The preparation of the azavinylogous orthoamide 4a is described. The thermolysis of 3 and 4a , resp., gives rise to the formation of the triaminopyrimidine 67 . Treatment of 1a with lithiumdiisopropylamide affords the triaminopyrazine 68 , which can also be obtained by thermolysis of 3 in the presence of sodium hydride. Azavinylogous carbenes are thought to be the intermediates.     

Glyco-Steroidal Amphiphiles (GSAs) for Membrane Protein Structural Study

Integral membrane proteins pose considerable challenges to high resolution structural analysis. Maintaining membrane proteins in their native state during protein isolation is essential for structural study of these bio-macromolecules. Detergents are the most commonly used amphiphilic compounds for stabilizing membrane proteins in solution outside a lipid bilayer. We previously introduced a glyco-diosgenin (GDN) detergent that was shown to be highly effective at stabilizing a wide range of membrane proteins. This steroidal detergent has additionally gained attention due to its compatibility with membrane protein structure study via cryo-EM. However, synthetic inconvenience limits widespread use of GDN in membrane protein study. To improve its synthetic accessibility and to further enhance detergent efficacy for protein stabilization, we designed a new class of glyco-steroid-based detergents using three steroid units: cholestanol, cholesterol and diosgenin. These new detergents were efficiently prepared and showed marked efficacy for protein stabilization in evaluation with a few model membrane proteins including two G protein-coupled receptors. Some new agents were not only superior to a gold standard detergent, DDM (n-dodecyl-β-d -maltoside), but were also more effective than the original GDN at preserving protein integrity long term. These agents represent valuable alternatives to GDN, and are likely to facilitate structural determination of challenging membrane proteins.     

Partialsynthesen von Cardenoliden und Cardenolid-Analogen. VI. (20R)- und (20S)-Cardanolide

Partial Syntheses of Cardenolides and Cardenolide Analogues. VI. (20R)- and (20S)-Cardanolides (20R)-Dihydrodigitoxigenin ( 2 ) and (20S)-dihydrodigitoxigenin ( 4 ) as well as their 3-acetates 3 and 5 , respectively, were synthesized by catalytic hydrogenation of the appropriate cardenolides and separation by column chromatography on silica of the mixtures of stereoisomers. Hydroxymethylation of 3 and 5 followed by selective elimination yielded (20S)- and (20R)-14-hydroxy-22-methylene-5β,14β-cardanolide 3-acetate ( 10 and 16 ), respectively. The biological activities of the synthesized 20-stereoisomeric cardanolides are investigated and discussed. Cardanolides 10 and 16 have a strong inhibitory activity on the proliferation of Ehrlich ascites carcinoma cells in suspension culture.     

Optical and Mechanical Properties of Thin PTFE Films,Deposited from a Gas Phase

Thin polytetrafluoroethylene (PTFE) films are produced by deposition from a gas phase by two methods: electron-enhanced vacuum deposition (EVD) and EVD + low-temperature plasma (LTP). Structure, morphology, and composition of the films are studied by IR spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. They are close to the structure of bulk PTFE. The roughness of the films’ surface is changed with gas pressure and LTP power variations. Films are transparent from UV to near-infrared regions. Refractive and extinction indices and their anisotropy are measured by spectral ellipsometry. They are tuned by variations of deposition conditions. Hardness and Young modulus of the films are increased if EVD + low power LTP is used for film deposition. Use of EVD + LTP also increases thermal stability of the films. Contact angle of the films corresponds to the bulk PTFE. The PTFE molecules oriented are preferentially in perpendicular direction to the substrate surface.