Synthesis and Stereochemical Properties of Chiral Square Complexes of Iron(II)

Der hexadentate und ditopische Ligand 2,5-Bis([2,2']bipyridin-6-yl)pyrazin bildet bei der Selbstorganisationsreaktion mit Fe²⁺-Ionen einen chiralen, quadratförmigen Tetramerkomplex. Das Racemat dieses Komplexes wurde mit Hilfe von Antimonyltartrat in die Enantiomere getrennt. Die Reinheit des Enantiomers wurde durch NMR-Spektroskopie unter Zuhilfenahme eines chiralen, diamagnetischen Shift-Reagenzes untersucht, wie auch duch die Beobachtung des Circulardichroismus (CD). Das CD-Spektrum wurde zudem mit zeitabhängiger Dichtefunktionaltheorie berechnet, wobei die vorhergesagte Korrelation zwischen CD-Spektrum und Konfiguration des Komplexes durch Röntgenstrukturanalyse bestätigt wurde. Die Verwendung einer chiralisierten Variante des Liganden ergab den entsprechenden Eisenkomplex in diastereomerenreiner Form.The hexadentate, and ditopic ligand 2,5-bis([2,2']bipyridin-6-yl)pyrazine yields a chiral, tetrameric, square-shaped, self-assembled species upon complexation with Fe²⁺ ions. The racemate of this complex was resolved with antimonyl tatrate as the chiral auxiliary. The purity of the enantiomer was determined by NMR spectroscopy, by using a chiral, diamagnetic shift reagent, and by circular dichroism (CD). The CD spectrum was also calculated by time-dependent density functional theory, and the correlation that was found between CD spectrum and configuration was confirmed by X-ray cristallography. When a chiralised version of the ligand was used instead, the corresponding iron complex was obtained in diastereomerically pure form

Self-assembly of Ag(I) helicates with new enantiopure 5,6-Chiragen type ligands

Two new chiral bis-bidentate, C2-symmetrical ligands belonging to the Chiragen family have been synthesised and characterised. They are designed for polynuclear self-assemblies since the two (−)-5,6-pinenebipyridines units are connected by bridges whose length and rigidity avoids the coordination of the bipyridine moieties to the same metal centre. The ligand L1 with a 1,4-dimethylene naphthalene bridge leads, by complexation with Ag(I) cations, to a polymeric, single stranded helix. The helical pitch contains five metal centers, two consecutive metal centers being connected by a bis-bidentate, helically wrapped ligand, one up and the other down resulting in a coordination number four. The chirality (Λ) around each metal centre is controlled by the six asymmetric carbons of the ligands and the homochirality of the metal centers gives rise to a P orientation at the helix level. The 1H-NMR measurements of these species in solution indicate a temperature dependent behaviour pointing out possible equilibria between various [AgnLn]n+ fragments as confirmed by MS-spectroscopy. The ligand L2 with a 4,4′-dimethylene-1,1′-biphenyl bridge reacts with Ag(I) and lead to well resolved and temperature independent 1H- NMR spectra suggesting the formation of a circular helicate

Do differences in profiling criteria bias performance measurements? Economic profiling of medical clinics under the Korea National Health Insurance program: An observational study using claims data

<p>Abstract</p> <p>Background</p> <p>With a greater emphasis on cost containment in many health care systems, it has become common to evaluate each physician's relative resource use. This study explored the major factors that influence the economic performance rankings of medical clinics in the Korea National Health Insurance (NHI) program by assessing the consistency between cost-efficiency indices constructed using different profiling criteria.</p> <p>Methods</p> <p>Data on medical care benefit costs for outpatient care at medical clinics nationwide were collected from the NHI claims database. We calculated eight types of cost-efficiency index with different profiling criteria for each medical clinic and investigated the agreement between the decile rankings of each index pair using the weighted kappa statistic.</p> <p>Results</p> <p>The exclusion of pharmacy cost lowered agreement between rankings to the lowest level, and differences in case-mix classification also lowered agreement considerably.</p> <p>Conclusions</p> <p>A medical clinic may be identified as either cost-efficient or cost-inefficient, even when using the same index, depending on the profiling criteria applied. Whether a country has a single insurance or a multiple-insurer system, it is very important to have standardized profiling criteria for the consolidated management of health care costs.</p

A Single Amino Acid Mutation in SNAP-25 Induces Anxiety-Related Behavior in Mouse

Synaptosomal-associated protein of 25 kDa (SNAP-25) is a presynaptic protein essential for neurotransmitter release. Previously, we demonstrate that protein kinase C (PKC) phosphorylates Ser187 of SNAP-25, and enhances neurotransmitter release by recruiting secretory vesicles near to the plasma membrane. As PKC is abundant in the brain and SNAP-25 is essential for synaptic transmission, SNAP-25 phosphorylation is likely to play a crucial role in the central nervous system. We therefore generated a mutant mouse, substituting Ser187 of SNAP-25 with Ala using “knock-in” technology. The most striking effect of the mutation was observed in their behavior. The homozygous mutant mice froze readily in response to environmental change, and showed strong anxiety-related behavior in general activity and light and dark preference tests. In addition, the mutant mice sometimes exhibited spontaneously occurring convulsive seizures. Microdialysis measurements revealed that serotonin and dopamine release were markedly reduced in amygdala. These results clearly indicate that PKC-dependent SNAP-25 phosphorylation plays a critical role in the regulation of emotional behavior as well as the suppression of epileptic seizures, and the lack of enhancement of monoamine release is one of the possible mechanisms underlying these defects

Possible Conservation of the K -Quantum Number in Excited Rotating Nuclei

The \ensuremath{\gamma} cascades feeding into low-K and high-K bands in ${}^{163}$Er are investigated analyzing variances and covariance of the spectrum fluctuations. From a large data set of 1${0}^{9}$ triple coincidences, \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-K bands are different from those feeding the high-K bands. The persistence of the K-selection rules for the excited rotational bands within the angular momentum region 30\ensuremath{\Elzxh}\ensuremath{\le}I\ensuremath{\le}40\ensuremath{\Elzxh} is suggested as explanation

A genome-wide association study of type 2 diabetes in finns detects multiple susceptibility variants

Identifying the genetic variants that increase the risk of type 2 diabetes (T2D) in humans has been a formidable challenge. Adopting a genome-wide association strategy, we genotyped 1161 Finnish T2D cases and 1174 Finnish normal glucose-tolerant (NGT) controls with >315,000 single-nucleotide polymorphisms (SNPs) and imputed genotypes for an additional >2 million autosomal SNPs. We carried out association analysis with these SNPs to identify genetic variants that predispose to T2D, compared our T2D association results with the results of two similar studies, and genotyped 80 SNPs in an additional 1215 Finnish T2D cases and 1258 Finnish NGT controls. We identify T2D-associated variants in an intergenic region of chromosome 11p12, contribute to the identification of T2D-associated variants near the genes IGF2BP2 and CDKAL1 and the region of CDKN2A and CDKN2B, and confirm that variants near TCF7L2, SLC30A8, HHEX, FTO, PPARG, and KCNJ11 are associated with T2D risk. This brings the number of T2D loci now confidently identified to at least 10

Supramolecular Chemistry with Chiral Pyridine-Type Ligands

Chiral pyridine-type ligands are readily available in enantiomerically pure form from enantiopure natural products via a Kröhnke reaction. The ease of synthesis allows numerous variations of the ligands which all display a particular coordination behavior. By these means, it is possible to synthesize 'tunable' series of molecules. Thus, mononuclear, as well as self-assembled polynuclear species can be obtained in enantiopure form. With these ligands, a significant step towards the systematic development of stereoselective synthesis in coordination chemistry was achieved, leading to a class of compounds that hold interest for various kinds of applications