Methylamine stimulates the action of ricin toxin but inhibits that of diphtheria toxin

The action of ricin toxin was stimulated by addition of methylamine or some other amines, as shown by measuring the inhibition of protein synthesis of cultured cells by the toxin. Under the same conditions, however, the action of diphtheria toxin was completely inhibited by the amines. In a cell-free protein-synthesizing system, methylamine had no effect on the action of the A chain of ricin toxin and fragment A of diphtheria toxin. Studies on the interactions of 125I-labeled toxins with cells revealed that methylamine did not alter toxin-receptor bindings, but affected the entry of the toxins into the cells. Studies were also made on the effects of methylamine on the actions of two hybrid toxins, formed from a subunit of Wistaria floribunda lectin and fragment A of diphtheria toxin and the A chain of ricin toxin, respectively. Results suggested that the processes of entry of ricin toxin and diphtheria toxin, or at least parts of these processes, are different.     

Phototoxicities Caused by Continuous Light Exposure Were Not Induced in Retinal Ganglion Cells Transduced by an Optogenetic Gene

The death of photoreceptor cells is induced by continuous light exposure. However, it is unclear whether light damage was induced in retinal ganglion cells with photosensitivity by transduction of optogenetic genes. In this study, we evaluated the phototoxicities of continuous light exposure on retinal ganglion cells after transduction of the optogenetic gene mVChR1 using an adeno-associated virus vector. Rats were exposed to continuous light for a week, and visually evoked potentials (VEPs) were recorded. The intensities of continuous light (500, 1000, 3000, and 5000 lx) increased substantially after VEP recordings. After the final recording of VEPs, retinal ganglion cells (RGCs) were retrogradely labeled with a fluorescein tracer, FluoroGold, and the number of retinal ganglion cells was counted under a fluorescent microscope. There was no significant reduction in the amplitudes of VEPs and the number of RGCs after exposure to any light intensity. These results indicated that RGCs were photosensitive after the transduction of optogenetic genes and did not induce any phototoxicity by continuous light exposure.     

Effect of antioxidant contained in poly(ethylene glycol) on cell fusion

The effect of antioxidants contained in poly(ethylene glycol) (PEG) on cell fusion was studied using L929 cells in the monolayer state. Hydroquinone monomethyl ether (HQME), 2-mercaptobenzimidazole (MB), butyl hydroxyanisole (BHA) and 2,6-di-(t-butyl)-4-methylphenol (BHT) were chosen from the antioxidants that have currently been used to protect commercially available PEG from oxidation. Cell culture was conducted in 40% w/w aqueous solution of PEG with a molecular weight of 3000 in the presence of different concentrations of antioxidants. BHA clearly enhanced membrane fusion of L929 cells with increasing concentration in PEG solution, whereas HQME, MB and BHT had no significant effect on cell fusion. The enhancement of cell fusion by BHA might be ascribed to balanced hydrophobicity and high water solubility in comparison with the other three antioxidants.     

Environmental protection: researches in National Institute of Radiological Sciences

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.     

Quantitative analysis for reaction between epoxidized natural rubber and poly (L‐lactide) through 1H‐NMR spectroscopy

Reaction between epoxidized natural rubber and poly(L ‐lactide) (PLLA) was investigated quantitatively in terms of conversion of the epoxidized natural rubber. The epoxidized natural rubber was prepared by epoxidation of high ammonia natural rubber (HA‐NR) or deproteinized natural rubber (DPNR) with peracetic acid followed by depolymerization with ammonium persulfate. The resulting liquid HA‐NR having epoxy group (LENR) or liquid DPNR having epoxy group (LEDPNR) were subjected to heating at 473 K for 20 min, after blending with PLLA. The products were characterized through morphology observation, DSC measurement, and ¹H‐NMR spectroscopy. The conversions of the rubbers were estimated from intensity ratio of signals in ¹H‐NMR spectrum for the products after removing unreacted rubber with toluene. Difference in the estimated conversion between the LENR/PLLA and LEDPNR/PLLA blends was interpreted in relation to proteins present in the rubber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kinetics of solid acid catalyzed 1-octene reactions with TiO2 in sub- and supercritical water

Acid catalyzed reactions of 1-octene on TiO₂ in sub- and supercritical water were investigated (T = 250-450 °C, P = 11-33 MPa). The main products were 2-octene and 2-octanol. Additionally, other liner C₈ alkenes and liner secondary C₈ alcohols were produced as by-products. Through kinetic analysis, acid catalyzed reactions can divide into the reaction catalyzed by Lewis acidic sites on TiO₂ and the reaction catalyzed by protons produced by the dissociation of water molecules. Each type of the reaction is affected by water density or ionic product of water, respectively, therefore, reaction mechanism changes with temperature and pressure. From the contribution of each reaction type, the temperature dependence of cis/trans ratio of produced 2-octene could also be explained.     

Key factors in tissue engineering

Tissue engineering is an emerging biomedical form of engineering aiming at regeneration of natural tissues or creation of biological substitutes for defective or lost tissues and organs using cells of different species. It is essential for the tissue self-regeneration, for instance, to provide a space necessary for regeneration with certain materials and technologies. This article overviews such key factors required for tissue engineering.     

Effect of weld line direction and paint orientation on corrosion and paint deterioration characteristics of welded part of steel

One thousand two hundred cycles of accelerated exposure experiment with combined salt water spray simulating atmospheric corrosion was performed for investigating the effect of weld line direction and paint orientation on the corrosion and paint deterioration characteristics of welded part of the steel. The corrosion depth of the weld toe of transverse weld line became 1.35 times as large as that of the base metal part because of the remained salt water on the weld toe. The coating thickness at the weld toe became thin by vertically painting on the transverse weld line. When the scribe line was installed at the thin painted weld toe under the transverse weld line, the paint blister area became 15% larger than that of the base metal part. The paint coating thickness at the weld toe in different weld line directions and paint orientations should be confirmed and ensured from the viewpoints of manufacturing and maintaining steel structures.     

Microstructure of a Molybdenum Nitride Layer Formed by Nitriding Molybdenum Metal

For pure molybdenum nitrided at 1373 K in NH₃ gas, microstructural observations of a molybdenum nitride layer were conducted through a transmission electron microscope. The molybdenum nitride layer consisted of two molybdenum nitrides: an outer one of γ-Mo₂N and an inner one of β-Mo₂N. A great number of (011)[0     1] type twins were observed in the β-Mo₂N phase, whereas the microstructure of the γ-Mo₂N phase was almost free from lattice defects except for slightly observed {111}〈112〉 type twin.     

Tissue compatibility of polylactic acids in the skeletal site

This study was undertaken to examine the osseous tissue compatibility of polylactic acid (PLA) with properties of bioabsorbability and plasticity. Two kinds of granular PLA with different molecular weight (PLA-H: 28 000 MW, PLA-L: 10 600 MW) were implanted into rat tibiae and light microscopic sections were prepared at 1, 2, 4, 8, 16, and 24 weeks following surgery. The tissue compatibility of the PLAs was compared with that of hydroxyapatite (HAP) which is a non-absorbable biocompatible material. After implantation, both PLAs were gradually absorbed and replaced by marrow tissue at 24 weeks. PLA-H degraded slower than PLA-L. New bone formation was observed around each PLA by 4 weeks, and a vast amount of bone deposited on PLA-H at 16 weeks. Phagocytic reactions to the PLAs were noted, however, severe inflammation was not seen. HAP was not absorbed and bone surrounded it throughout the experiment. These results indicate good tissue compatibility of PLA as a bioabsorbable material at the skeletal site.