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53 result(s) for "Lyssenko, K A"
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Crystal Structure and Low-Temperature Structural Phase Transition of the Iron(III) Oxopropionate Nitrate Fe3O(H2O)3Prop6(NO3)·(HNO3)
A compound [Fe 3 O(H 2 O) 3 Prop 6 ](NO 3 )·(HNO 3 ) ( 1 ; Prop – is the C 2 H 5 COO – propionate) is prepared by the interaction of metallic iron and Fe(NO 3 ) 3 with concentrated propionic acid; the crystal structure of this compound is determined by single-crystal XRD at 100 K, 200 K, and 300 K. The experimental data show that the structure of 1 is a packing of complex cations [Fe 3 O(H 2 O) 3 Prop 6 ] + and nitrate anions with nitric acid molecules in packing voids. It is shown for the first time by polythermal XRD that 1 undergoes a structural phase transition manifested as partial ordering of aliphatic substituents in anionic ligands, changes in the configuration of NO 2 –OH⋯O–NO 2 hydrogen bonds, and lowering of crystallographic symmetry of [Fe 3 O(H 2 O) 3 Prop 6 ] + complex cations. Thermal expansion of the crystal structure of 1 is studied in the temperature range 100-300 K; the experimental data show that the unit cell parameter b changes nonmonotonically upon heating and exhibits pronounced regions of positive and negative thermal expansion.
Samarium Hydrogen Iodate, Sm(IO3)3·HIO3: Synthesis and Characterization
Samarium hydrogen iodate Sm(IO 3 ) 3 ·HIO 3 was successfully synthesized by the unconventional low-temperature solution-melt method, its structure was determined by X-ray diffraction analysis of single crystals. This compound crystallizes in the monoclinic space group P 2 1 / c with lattice parameters: a  = 10.4637(6) Å, b  = 7.4629(5) Å, c  = 14.0174(13) Å, β = 110.53(0), Z  = 6. In the studied structure, samarium atoms are surrounded by 8 oxygen atoms in a polyhedron in the form of a distorted square antiprism. The iodate groups are linked through common oxygen atoms of the SmO 8 antiprism into a three-dimensional framework. The compound was characterized by X-ray diffraction, IR and NQR spectroscopy and EDX analysis.
Synthesis and characterization of a cross-linking monomer based on 1,3-diallyl-1,3-dibicyclo4.2.0octa-1,3,5-trien-3-yl-1,3-dimethyl-siloxane
New cross-linking monomer based on 1,3-diallyl-1,3-di[bicyclo[4.2.0]octa-1,3,5-trien-3-yl]-1,3-dimethyl-siloxane (BCB-All) was synthesized and its physical properties were studied. BCB-All was incorporated into copolymer with TGM-3 and PFHDA by two stage thermal polymerization. The cross-linking of the copolymers occurs by thermo-initiated ring-opening reaction of BCB at 120-200°C. Resulting BCB-All homopolymer, BCB-All-TGM-3 (50:50), and BCB-All-PFHDA (50:50) copolymers have high thermal stability (Td5%,=464°C, 322°C, 435°C respectively) and good dielectric properties (ε=2.34-2.48 at 10HHz).
Preparation of fluorinated 5,5′-dialkylsubstituted dipyrromethanes
A synthetic approach to novel fluorinated 5,5′-dialkyl-substituted dipyrromethanes based on acid-catalyzed condensation of the corresponding pyrroles and ketones was developed. High efficiency of this transformation for a wide range of pyrroles and ketones was demonstrated using trifluoromethanesulfonic acid as a catalyst. A series of novel fluorinated dipyrromethanes was obtained in high yields.
Anisotropy of exchange interactions in honeycomb ladder compound ReCl5
The Re5+(5d2) compounds possess large spin-orbital interaction which urges for large anisotropy, non-collinear structures and other phenomena. Here we present ReCl5 composed by separate Re2Cl10 units formed by edge-shared chlorine octahedra. It demonstrates the formation of antiferromagnetically ordered state in two steps at TN1 = 35.5 K and TN2 = 13.2 K seen in dc-, ac-magnetic susceptibility and in specific heat. At 4K it can be transformed to the state with spontaneous magnetic moment by relatively weak magnetic field m0H = 0.5 T via metamagnetic phase transition. Ab initio calculations give anisotropic ferromagnetic exchange interactions J1 and J2 within and between rhenium pairs forming the zig-zag chains along the a-axis. Pairs of zig-zag chains are coupled by ferromagnetic interaction J3 along the c-axis into magnetic honeycomb ladders. The ladders are coupled by significantly weaker interaction J4.
First Trifluoromethylated Phenanthrolinediamides: Synthesis, Structure, Stereodynamics and Complexation with Ln(III)
The first examples of 1,10-phenanthroline-2,9-diamides bearing CF3-groups on the side amide substituents were synthesized. Due to stereoisomerism and amide rotation, such complexes have complicated behavior in solutions. Using advanced NMR techniques and X-ray analysis, their structures were completely elucidated. The possibility of the formation of complex compounds with lanthanoids nitrates was shown, and the constants of their stability are quantified. The results obtained are explained in terms of quantum-chemical calculations.
Reduced expression of OXPHOS and DNA damage genes is linked to protection from microvascular complications in long-term type 1 diabetes: the PROLONG study
Type 1 diabetes is a chronic autoimmune disease requiring insulin treatment for survival. Prolonged duration of type 1 diabetes is associated with increased risk of microvascular complications. Although chronic hyperglycemia and diabetes duration have been considered as the major risk factors for vascular complications, this is not universally seen among all patients. Persons with long-term type 1 diabetes who have remained largely free from vascular complications constitute an ideal group for investigation of natural defense mechanisms against prolonged exposure of diabetes. Transcriptomic signatures obtained from RNA sequencing of the peripheral blood cells were analyzed in non-progressors with more than 30 years of diabetes duration and compared to the patients who progressed to microvascular complications within a shorter duration of diabetes. Analyses revealed that non-progressors demonstrated a reduction in expression of the oxidative phosphorylation (OXPHOS) genes, which were positively correlated with the expression of DNA repair enzymes, namely genes involved in base excision repair (BER) machinery. Reduced expression of OXPHOS and BER genes was linked to decrease in expression of inflammation-related genes, higher glucose disposal rate and reduced measures of hepatic fatty liver. Results from the present study indicate that at transcriptomic level reduction in OXPHOS, DNA repair and inflammation-related genes is linked to better insulin sensitivity and protection against microvascular complications in persons with long-term type 1 diabetes.
Mechanisms by which common variants in the TCF7L2 gene increase risk of type 2 diabetes
Genetic variants in the gene encoding for transcription factor-7-like 2 (TCF7L2) have been associated with type 2 diabetes (T2D) and impaired beta cell function, but the mechanisms have remained unknown. We therefore studied prospectively the ability of common variants in TCF7L2 to predict future T2D and explored the mechanisms by which they would do this. Scandinavian subjects followed for up to 22 years were genotyped for 3 SNPs (rs7903146, rs12255372, and rs10885406) in TCF7L2, and a subset of them underwent extensive metabolic studies. Expression of TCF7L2 was related to genotype and metabolic parameters in human islets. The CT/TT genotypes of SNP rs7903146 strongly predicted future T2D in 2 independent cohorts (Swedish and Finnish). The risk T allele was associated with impaired insulin secretion, incretin effects, and enhanced rate of hepatic glucose production. TCF7L2 expression in human islets was increased 5-fold in T2D, particularly in carriers of the TT genotype. Overexpression of TCF7L2 in human islets reduced glucose-stimulated insulin secretion. In conclusion, the increased risk of T2D conferred by variants in TCF7L2 involves the enteroinsular axis, enhanced expression of the gene in islets, and impaired insulin secretion.
Replication and cross-validation of type 2 diabetes subtypes based on clinical variables: an IMI-RHAPSODY study
Aims/hypothesisFive clusters based on clinical characteristics have been suggested as diabetes subtypes: one autoimmune and four subtypes of type 2 diabetes. In the current study we replicate and cross-validate these type 2 diabetes clusters in three large cohorts using variables readily measured in the clinic.MethodsIn three independent cohorts, in total 15,940 individuals were clustered based on age, BMI, HbA1c, random or fasting C-peptide, and HDL-cholesterol. Clusters were cross-validated against the original clusters based on HOMA measures. In addition, between cohorts, clusters were cross-validated by re-assigning people based on each cohort’s cluster centres. Finally, we compared the time to insulin requirement for each cluster.ResultsFive distinct type 2 diabetes clusters were identified and mapped back to the original four All New Diabetics in Scania (ANDIS) clusters. Using C-peptide and HDL-cholesterol instead of HOMA2-B and HOMA2-IR, three of the clusters mapped with high sensitivity (80.6–90.7%) to the previously identified severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD) and mild obesity-related diabetes (MOD) clusters. The previously described ANDIS mild age-related diabetes (MARD) cluster could be mapped to the two milder groups in our study: one characterised by high HDL-cholesterol (mild diabetes with high HDL-cholesterol [MDH] cluster), and the other not having any extreme characteristic (mild diabetes [MD]). When these two milder groups were combined, they mapped well to the previously labelled MARD cluster (sensitivity 79.1%). In the cross-validation between cohorts, particularly the SIDD and MDH clusters cross-validated well, with sensitivities ranging from 73.3% to 97.1%. SIRD and MD showed a lower sensitivity, ranging from 36.1% to 92.3%, where individuals shifted from SIRD to MD and vice versa. People belonging to the SIDD cluster showed the fastest progression towards insulin requirement, while the MDH cluster showed the slowest progression.Conclusions/interpretationClusters based on C-peptide instead of HOMA2 measures resemble those based on HOMA2 measures, especially for SIDD, SIRD and MOD. By adding HDL-cholesterol, the MARD cluster based upon HOMA2 measures resulted in the current clustering into two clusters, with one cluster having high HDL levels. Cross-validation between cohorts showed generally a good resemblance between cohorts. Together, our results show that the clustering based on clinical variables readily measured in the clinic (age, HbA1c, HDL-cholesterol, BMI and C-peptide) results in informative clusters that are representative of the original ANDIS clusters and stable across cohorts. Adding HDL-cholesterol to the clustering resulted in the identification of a cluster with very slow glycaemic deterioration.
Identification of biomarkers for glycaemic deterioration in type 2 diabetes
We identify biomarkers for disease progression in three type 2 diabetes cohorts encompassing 2,973 individuals across three molecular classes, metabolites, lipids and proteins. Homocitrulline, isoleucine and 2-aminoadipic acid, eight triacylglycerol species, and lowered sphingomyelin 42:2;2 levels are predictive of faster progression towards insulin requirement. Of ~1,300 proteins examined in two cohorts, levels of GDF15/MIC-1, IL-18Ra, CRELD1, NogoR, FAS, and ENPP7 are associated with faster progression, whilst SMAC/DIABLO, SPOCK1 and HEMK2 predict lower progression rates. In an external replication, proteins and lipids are associated with diabetes incidence and prevalence. NogoR/RTN4R injection improved glucose tolerance in high fat-fed male mice but impaired it in male db/db mice. High NogoR levels led to islet cell apoptosis, and IL-18R antagonised inflammatory IL-18 signalling towards nuclear factor kappa-B in vitro. This comprehensive, multi-disciplinary approach thus identifies biomarkers with potential prognostic utility, provides evidence for possible disease mechanisms, and identifies potential therapeutic avenues to slow diabetes progression. There is an urgent need for biomarkers for type 2 diabetes progression that provide a deeper understanding of the disease process. Here, the authors identify biomarkers in three molecular classes, replicate them in other cohorts and explore top protein biomarkers in detail in functional studies.