Internal Stress in Electrodeposited PbO₂

The change of internal stress in the electrodeposited PbC₂ from a lead nitrate bath was observed by measuring the deflection of a thin platinum anode during electrodeposition of PbC₂ on one side of it. The crystal structure of the deposits was determined by X-ray diffraction. After the electrodeposition, the change of deflection of the deposited Pb₂ was observed under the following conditions : a) Keep the deposited PbO₂ in air or in a lead nitrate bath at constant temperatures. b) Discharge the cell, Pt/PbNO₃ electrolyte/PbO₂ deposit, by connecting it to an external circuit with some resistance. The results obtained are summarized as follows : 1) The crystal structure of α-PbO₂ was observed in the deposits which had deflected in the direction of contraction during electrodeposition, and β-PbO₂ was observed in the deposits which had deflected in the direction of expansion during electrodeposition. 2) After the electrodeposition, the deposits deflected gradually in the direction of expansion when they were kept in air or left in the bath. The amount of deflection of the deposits of α-PbO₂ was larger than that of the deposits of β-PbO₂ within the same time duration. 3) The electrodeposited PbO₂ deflected in the direction of expansion by discharging the cell, and the amount of deflection of the deposits of α-PbO₂ was larger than that of the deposits of β-PbO₂

高圧氷の構造相転移

取得学位：博士(理学)，学位授与番号：博甲第200号，学位授与年月日：平成9年3月25日,学位授与年：199

Bovine Insulin Filaments Induced by Reducing Disulfide Bonds Show a Different Morphology, Secondary Structure, and Cell Toxicity from Intact Insulin Amyloid Fibrils

AbstractAmyloid fibrils are associated with more than 20 diseases, including Alzheimer's disease and type II diabetes. Insulin is a 51-residue polypeptide hormone, with its two polypeptide chains linked by one intrachain and two interchain disulfide bonds, and has long been known to self-assemble in vitro into amyloid fibrils. We demonstrate here that bovine insulin forms flexible filaments in the presence of a reducing agent, Tris (2-carboxyethyl) phosphine. The insulin filaments, possibly formed due to partial reduction of S-S bonds in insulin molecules, differ from intact insulin fibrils in terms of their secondary structure. The insulin filaments were determined to have an antiparallel β-sheet structure, whereas the insulin fibrils have a parallel β-sheet structure. Of importance, the cell toxicity of the insulin filaments was remarkably lower than that of the insulin fibrils. This finding supports the idea that cell toxicity of amyloids correlates with their morphology. The remarkably low toxicity of the filamentous structure should shed new light on possible pharmacological approaches to the various diseases caused by amyloid fibrils

KF-1 Ubiquitin Ligase: An Anxiety Suppressor

Anxiety is an instinct that may have developed to promote adaptive survival by evading unnecessary danger. However, excessive anxiety is disruptive and can be a basic disorder of other psychiatric diseases such as depression. The KF-1, a ubiquitin ligase located on the endoplasmic reticulum (ER), may prevent excessive anxiety; kf-1−/− mice exhibit selectively elevated anxiety-like behavior against light or heights. It is surmised that KF-1 degrades some target proteins, responsible for promoting anxiety, through the ER-associated degradation pathway, similar to Parkin in Parkinson's disease (PD). Parkin, another ER-ubiquitin ligase, prevents the degeneration of dopaminergic neurons by degrading the target proteins responsible for PD. Molecular phylogenetic studies have revealed that the prototype of kf-1 appeared in the very early phase of animal evolution but was lost, unlike parkin, in the lineage leading up to Drosophila. Therefore, kf-1−/− mice may be a powerful tool for elucidating the molecular mechanisms involved in emotional regulation, and for screening novel anxiolytic/antidepressant compounds

Synthesis of Novel Polymers Containing Fluorenes and Their Gas Permeability

To develop new membrane materials, poly(fluoreneethynylene)s [PFEs] having alkyl groups at 9-position of fluorene were synthesized by ADIMET polymerization. PFEs with 2-ethylhexyl groups (2a) and dodecyl groups (2b) were obtained in high yields and their weight-average molecular weights were as high as 524,000 and 781,000 , respectively. The obtained polymers were soluble in CHCI3 and partly soluble in toluene and THF. Polymer (2d) was synthesized by Pd/Cu-catalyzed polymerization. The free-standing membranes of (2a) and (2d) could be prepared by solvent-casting method, and the gas permeability was measured. Their gas permeability was almost the same as that of poly(p-phenyleneethynvlen e)s reported previously

Nitration and Amination of Poly(diphenylacetylene)s and Their Properties

Poly[1-phenyl-2-[p-(tritnethylsilyl)phenyl]acetylene] [PTMSDPA] was synthesized by metathesis polymerization. PTMSDPA was nitrated using the mixture of sulfuric acid and nitric acid to give a nitrated polymer. Amination of the nitrated polymer was achieved by the reduction of nitro groups with SnCl_2 • 2H_2 O using polymer membrane. Nitration and Amination were confirmed by comparison of IR spectra before and after reaction, although the molecular weights of polymers were decreased during nitration reaction. Nitrated poly(diphenylacetylene) exhibited high gas permeability. Aminated polymers was much higher the CO_2 permselectivity of than that of the other poly(diphenylacetylene)s. Aminated polymers exhibited high CO_2 permselective and relatively high gas permeability, and hence they are promising candidates for CO_2 separation membranes

Synthesis of Trifunctional Poly(propylene glycol) with Acetal Linkages and Properties of Chemically Recyclable Crosslinked Polyurethanes Prepared Therefrom

The synthesis and characterization of chemically recyclable crosslin.ked polyurethanes were studied in this work. Acetal units were introduced into polypropylene glycol having three hydroxyl terminal groups (PPG) by the reaction of the hydroxy groups of PPG with 4-acetoxybutyl vinyl ether followed by conversion of the acetate groups into hydroxy groups. Crosslinked polyurethanes were prepared by the reaction of the acetal-containing polyols (PPG-acetal-OH) with tolylene diisocyanates (TDI) at 120 °C under vacuum. The obtained polyurethanes formed elastomeric films and exhibited good mechanical properties. The treatment of the polyurethane films with aqueous acid at room temperature caused smooth hydrolysis of their acetal units to give PPG as a degradation product

Variants of C-C Motif Chemokine 22 (CCL22) Are Associated with Susceptibility to Atopic Dermatitis: Case-Control Studies

Atopic dermatitis (AD) is a common inflammatory skin disease caused by multiple genetic and environmental factors. AD is characterized by the local infiltration of T helper type 2 (Th2) cells. Recent clinical studies have shown important roles of the Th2 chemokines, CCL22 and CCL17 in the pathogenesis of AD. To investigate whether polymorphisms of the CCL22 gene affect the susceptibility to AD, we conducted association studies and functional studies of the related variants. We first resequenced the CCL22 gene and found a total of 39 SNPs. We selected seven tag SNPs in the CCL22 gene, and conducted association studies using two independent Japanese populations (1st population, 916 cases and 1,032 controls; 2nd population 1,034 cases and 1,004 controls). After the association results were combined by inverse variance method, we observed a significant association at rs4359426 (meta-analysis, combined P = 9.6×10−6; OR, 0.74; 95% CI, 0.65–0.85). Functional analysis revealed that the risk allele of rs4359426 contributed to higher expression levels of CCL22 mRNA. We further examined the allelic differences in the binding of nuclear proteins by electrophoretic mobility shift assay. The signal intensity of the DNA-protein complex derived from the G allele of rs223821, which was in absolute LD with rs4359426, was higher than that from the A allele. Although further functional analyses are needed, it is likely that related variants play a role in susceptibility to AD in a gain-of-function manner. Our findings provide a new insight into the etiology and pathogenesis of AD