Two Regioisomers of Endohedral Pyrrolidinodimetallofullerenes M2@Ih‐C80(CH2)2NTrt (M=La,Ce; Trt=trityl): Control of Metal Atom Positions by Addition Positions

The two regioisomers of endohedral pyrrolidinodimetallofullerenes M₂@I_h‐C₈₀(CH₂)₂NTrt (M=La, Ce; Trt=trityl) were synthesized, isolated, and characterized. X‐ray crystallographic analyses of [6,6]‐La₂@I_h‐C₈₀(CH₂)₂NTrt and [6,6]‐Ce₂@I_h‐C₈₀(CH₂)₂NTrt revealed that the encapsulated metal atoms are located at the slantwise positions on the mirror plane that parallels the pyrrolidine ring. Paramagnetic NMR analyses of [6,6]‐ and [5,6]‐Ce₂@I_h‐C₈₀(CH₂)₂NTrt were also carried out to clarify the metal positions. As for the [6,6]‐adduct, the metal positions obtained by paramagnetic NMR analysis agree well with the X‐ray structure. In contrast, paramagnetic NMR analysis of the [5,6]‐adduct showed that the two Ce atoms are collinear with the pyrrolidine ring. We also compared the observed paramagnetic effects of the pyrrolidinodimetallofullerenes with those of other cerium‐encapsulating fullerene derivatives such as bis‐silylated Ce₂@I_h‐C₈₀ and a carbene adduct of Ce₂@I_h‐C₈₀. We found that the metal positions can be explained by the electrostatic potential maps of the corresponding [6,6]‐ and [5,6]‐adducts of [I_h‐C₈₀(CH₂)₂NTrt]^6?. These findings clearly show that metal positions inside fullerene cages can be controlled by means of the addition positions of the addends. In addition, the radical anions of the pyrrolidinodimetallofullerenes were prepared by bulk controlled‐potential electrolysis and characterized by X‐band EPR spectral study.     

Synthesis and photo DNA-damaging activities of fluoroquinolone analogues

Fluoroquinolone (FLQ) analogues were synthesized and their DNA photocleaving abilities were assayed. The photo-bioactivities of the fluoroquinolones were dependent on the carbonyl moieties attached to quinolone ring.     

Effect of cyclodextrin on allergic action of the PiCl-induced in NC/Nga mice

Itching dermatitis, which is very similar to human atopic dermatitis, arises spontaneously in NC/Nga mice. Changes in lesional skin and the plasma concentration of IgE during the development of atopic dermatitis-like disease up to 8 weeks after the start of picryl chloride (PiCl) in NC/Nga mice were examined. In the mice which atopic dermatitis had been induced, 28-day administration of α cyclodextrin (α CD) significantly inhibited aggravation of detmatitis without having effects on body weight. Clinical signs and symptoms seen in PiCl treated NC/Nga mice began with erythema and haemorrhage, following oedema, superficial erosion, deep excoriation, scaling and dryness of the skin. An increase was observed in the number of mast cells and eosinophil infiltration in the lesional skin. Almost human patients with nasal inflammation or bronchial asthmatics symptoms disappeared by oral administration of α CD (5 mg/day) for 2 month. These results suggest that α CD is useful for treatment of human atopic dermatitis.     

Dynamic character of human growth hormone and its receptor: normal mode analysis

Human growth hormone (hGH) induces dimerization of its binding protein (hGHbp). hGH binds to the first hGHbp (bp1) on site 1, and then the hGH-bp1 heterodimer complex binds to the second hGHbp (bp2) on site 2. Although the interactions of hGH and hGHbps have been studied from different viewpoints, few studies from a dynamic viewpoint have been reported. Especially, since in the SCOP domain database hGHbp is classified as two clear immunoglobulin-like domains, it is of interest to understand how hGH interacts with the hGHbp domains. Therefore, we carried out normal mode analysis (NMA) of free hGH, free bp1, free bp2, and the hGH-bp1 heterodimer complex, as well as the hGH-bp1-bp2 ternary complex to investigate how the dynamics of the proteins change before and after forming the complexes. NMA showed that the domain motion between the N-terminal and the C-terminal domains of free bp1 markedly decreased after binding to hGH, and that the domain motion of bp2 decreased similarly after binding to the hGH-bp1 heterodimer complex. The present study demonstrates that hGH regulates the inter-domain motions of both hGHbps.     

Design and synthesis of dual inhibitors of acetylcholinesterase and serotonin transporter targeting potential agents for Alzheimer's disease

Highly efficient acetylcholinesterase (AChE) and serotonin transporter (SERT) dual inhibitors, (S)-4 and (R)-13 were designed and synthesized on the basis of the hypothetical model of AChE active site. Both compounds showed potent inhibitory activities against AChE and SERT. [structure: see text]     

Synthesis and characterization of 1,3,4-oxadiazole-containing polyazomethines

Novel 1,3,4-oxadiazole-containing polyazomethines were synthesized by the polycondensation of diamines, 2,5-bis (m-aminophenyl)-1,3,4-oxadiazole (BMAO) and 2,5-bis (p-aminophenyl)-1,3,4-oxadiazole (BPAO), with aromatic dialdehydes, isophthalaldehyde and terephthalaldehyde, in m-cresol at 20°C. These polymers were yellow to orange in color and had reduced viscosities up to 1.13 dL/g and electric conductivity as high as 10^?11?10^?12 S cm^?1. All the polyazomethines were insoluble in common organic solvents but dissolved in concentrated sulfuric acid. Thermogravimetry showed that thermal degradation started at around 400°C in air and nitrogen atmospheres. Doping with iodine markedly increased the conductivity and produced the black-colored semiconductive polyazomethines with a maximum conductivity of the order of 10^?6 S cm^?1. Electronic spectra of the undoped polymers indicated a large bathochromic shift of the absorption maxima due to C?N bonds of the monomer diamines (285 nm for BMAO and 315 nm for BPAO). This suggests that π-electrons of the polymers are extensively delocalized along the main chain.     

Degradation mechanism of scandia-stabilised zirconia electrolytes: Discussion based on annealing effects on mechanical strength,ionic conductivity,and Raman spectrum

In the present study, the mechanical strength as well as the ionic conductivity of the scandia- and ytterbium oxide-codoped zirconia electrolyte is investigated during annealing. Based on the annealing effect on both properties, the degradation mechanism is discussed. The X-ray diffraction and Raman spectroscopic analyses confirmed that annealing enhanced the tetragonal phase content in the samples which initially contained the tetragonal phase. The samples with the rhombohedral phase showed no phase changes. The samples initially with the tetragonal phase showed a significant decrease in the conductivity but an increase in the strength whereas the samples with the rhombohedral phase generally showed no change and the ones with the cubic phase showed slight decreases in both properties. From above results, the conductivity degradation of the sample with the tetragonal phase was attributed to two causes: the formation of low conductive but transformable t-phase from the high conductive t′-phase and the formation of t′-phase from the t″-phase. The annealing effect was little for the samples initially with rhombohedral phase and complex for the ones with cubic phase.     

Enlarged endolymphatic duct and sac syndrome: relationship between MR findings and genotype of mutation in Pendred syndrome gene

Pendred syndrome (PDS) is characterized by profound deafness in childhood, positive perchlorate challenge, and goiter. PDS is often associated with enlarged endolymphatic duct and sac (EEDS), and recently, PDS gene mutations have been reported even in those patients with EEDS without classic Pendred syndrome. In a previous report, the number of mutant alleles was correlated with the degree of subclinical thyroid abnormality, but not with hearing loss, in patients with missense mutation H723R. It also has been reported that the hearing loss in EEDS was not correlated with the EEDS volume, cochlear modiolar area, or signal intensity of the endolymphatic sac. We evaluated the correlations between the number of mutant alleles and these parameters in patients with EEDS to investigate the mechanisms underlying this condition. The study group was comprised of 16 Japanese patients with EEDS diagnosed by MR imaging. The H723R mutation was homozygous in six patients and heterozygous in six patients, with no mutation found in four patients. The modiolar area, EEDS volume, and signal intensity ratio (sac signal/cerebrospinal fluid signal) were not significantly correlated with the number of mutant alleles. PDS gene mutations may not be the only cause of EEDS, and the mechanisms underlying EEDS remain unclear.