Hinge sugar as a movable component of an excimer fluorescence sensor

[reaction: see text] The ring flip of a carbohydrate is employed for the tongs-like movable component of a metal ion sensor. A pair of separated pyrene groups attached to the carbohydrate component are placed side by side when it recognizes metal ions, affording excimer fluorescence. This novel molecular sensor is selective for Zn(2+) and Cd(2+).     

Direct observation of ferromagnetic spin polarization in gold nanoparticles

We report the first direct observation of ferromagnetic spin polarization of Au nanoparticles with a mean diameter of 1.9 nm using x-ray magnetic circular dichroism (XMCD). Owing to the element selectivity of XMCD, only the gold magnetization is explored. Magnetization of gold atoms as estimated by XMCD shows a good agreement with results obtained by conventional magnetometry. This evidences intrinsic spin polarization in nanosized gold.     

Mechanical property and molecular weight distribution changes with photo- and chemical-degradation on LDPE films

In order to clarify the effect of photo- and chemical-degradation on the structure of polyethylene materials, the change in molecular weight distribution and mechanical properties of photo- and chemical-degraded LDPE films were investigated. The molecular weight distribution was significantly changed with photo-exposing times, and the drastic change appeared especially for 8 days-exposed samples where the molecular weight of the high molecular weight fraction increased. However, the molecular weight of the lower molecular weight fraction was almost the same for all the photo-exposed films, irrespective of irradiation time, and also for chemical-degraded films. It is suggested that the molecular chains with a certain length, which consist of a crystal lamellae in spherulites, cannot be broken by photo-irradiation. Consequently, there would be threshold for the molecular weight in terms of photo-degradation process, and almost the same threshold can be observed for the chemical-etching films. Stress-strain curves were measured for photo-degraded films and their “quenched films after remolding” and “annealed films after remolding”, and chemical-degraded films.     

Development of highly stereoselective asymmetric 6pi-azaelectrocyclization of conformationally flexible linear 1-azatrienes. from determination of multifunctional chiral amines, 7-alkyl cis-1-amino-2-indanols, to application as a new synthetic strategy: formal synthesis of 20-epiuleine

The highly stereoselective asymmetric 6pi-azaelectrocyclization was achieved as a general synthetic method based on the reaction between the (E)-3-carbonyl-2,4,6-trienal compounds and the (-)-7-alkyl-cis-1-amino-2-indanol derivatives which are effective chiral amines. The 7-alkyl-substituted 2-indanol moiety of the cyclized products was efficiently removed by the novel manganese dioxide oxidation under remarkably mild conditions, and the method was successfully applied to the formal synthesis of optically active 20-epiuleine.     

Oily drug carriers in cancer chemotherapy. II. Preparation of viscous ethyl oleate for intraarterial infusion therapy and its disposition in rats and hamsters.

Viscous ethyl oleate (VEO) was prepared as an oil drug carrier by the addition of aluminum stearate or ethyl cellulose. Since the rate of shear of VEO containing aluminum stearate was greatly and nonlinearly changed against the shearing stress compared to that containing ethyl cellulose, the latter was used for subsequent microvascular and organ distribution experiments in rats and hamsters. For infusion into the carotid artery in hamsters, neat ethyl oleate (EO, 4cP) or VEOs of various apparent viscosities (40, 80, 120 cP-VEOs) embolized the vascular system in the cheek pouch, although arrival time to the site where the embolization was observed and the embolization period differed depending on the type of oily drug carrier. For infusion into the hepatic artery in rats, however, only 120 cP-VEO embolized the vascular system in the liver. After infusion of the oily drug carrier containing 3H-oleic acid into the artery of hamster cheek pouch and rat liver, 30-50% of the radioactivity was gradually eliminated within 48 h, whereas about 80% of the dose was rapidly eliminated after infusion to rat stomach and kidney. In addition, the amount of 120 cP-VEO remaining in each organ 48 h after infusion was higher than those of EO and 40 and 80 cP-VEOs. Histological observation after infusion in rat liver revealed that 120 cP-VEO slowly migrated from the artery or arteriole to the sinusoidal capillary region. These results suggest that 120 cP-VEO can be used as a drug carrier because of its function of vascular embolization and high retention in a targeted tissue.     

Intramolecular excimer fluorescence,its solvent dependence,and photodimerization of 1,2-dianthrylethanes

Both 1,2-di(1-anthryl)ethane (I) and 1,2-di(9-anthryl) ethane (II) show two types of excimer fluorescence spectra under different conditions; one with peak at 460 nm (type-1) and the other with peak at 530 nm (type-2). Furthermore, the type-1 excimer emission shows a peculiar dependence upon the solvent polarity.     

Chemical synthesis and isolation of UDP-2-deoxy glucose and galactose

2-Deoxy sugars are attractive compounds in synthetic chemistry with regard to reactivity and stereoselectivity. Moreover, their ability to inhibit enzymes and metabolism is significant in biology. In this study, uridine-5′-diphosphate (UDP)-2-deoxy glucose (11) and galactose (12) were synthesized chemically. These sugar donors for glycosyltransferases were obtained α-selectively via phosphorylation using thioglycosides, coupling reaction with uridine-5′-monophosphate (UMP)-morpholidate, and moderate deacetylation. Isolation was carried out by sequential silica-gel chromatography using two kinds of developing solvents in a refrigerator. The structures were elucidated from the NMR results. Investigation of stability showed that the synthesized UDP-2-deoxy sugars were hydrolyzed much faster in buffer (pH 4) than the natural UDP sugars.     

Environmental Radiation Monitoring after the Accidental Release from Bituminization Demonstration Facility

The fire and explosion of the Bituminization Demonstration Facility at PNC Tokai Works were occurred on March 11th, 1997. As soon as the fire occurred, environmental monitoring was started. The influence of accidental release was recognized from some samples of airborne dust and surface soil on site. No influence was recognized from the samples off site except the airborne dust collected at O-arai (20 km south). The official statement by the Nuclear Safety Commission of Japan was: "It was less than the value which has an influence on the environment and health."     

Affinity‐Labeling‐Based Introduction of a Reactive Handle for Natural Protein Modification

A new chemical method to site‐specifically modify natural proteins without the need for genetic manipulation is described. Our strategy involves the affinity‐labeling‐based attachment of a unique reactive handle at the surface of the target protein, and the subsequent selective transformation of the reactive handle by a bioorthogonal reaction to introduce a variety of functional probes into the protein. To demonstrate this approach, we synthesized labeling reagents that contain: 1) a benzenesulfonamide ligand that directs specifically to bovine carbonic anhydrase II (bCA), 2) an electrophilic epoxide group for protein labeling, 3) an exchangeable hydrazone bond linking the ligand and the epoxide group, and 4) an iodophenyl or acetylene handle. By incubating the labeling reagent with bCA, the reactive handle was covalently attached at the surface of bCA through epoxide ring opening. Either after or before removing the ligand by a hydrazone/oxime‐exhange reaction, which restores the enzymatic activity, the reactive handle incorporated could be derivatized by Suzuki coupling or Huisgen cycloaddition reactions. This method is also applicable to the target‐specific multiple modification in a protein mixture. The availability of various (photo)affinity‐labeling reagents and bioorthogonal reactions should extend the flexibility of this strategy for the site‐selective incorporation of many functional molecules into proteins.