Reduction mechanism of tioglycolic acid on keratin fibers using microspectrophotometry and FT-Raman spectroscopy

In order to investigate the reduction mechanism of thioglycolic acid (TG) on the keratin fibers, cross-sectional samples of white human hair treated with TG were prepared. The heterogeneous reaction between TG and keratin fibers involving the diffusion of TG into human hair was analyzed at the molecular level using microspectrophotometry and FT-Raman spectroscopy. The diffusion of TG into human hair clearly increased by increasing the treatment time and by raising pH. The TG relative concentration and the disconnected relative concentration of disulfide (–SS–) groups at various depths of the hair samples with pH 9.0 were in good agreement, indicating that the reaction rate (the disconnection of –SS– groups) was faster than the diffusion rate of TG into human hair. From these experiments, we demonstrated that TG diffuses gradually beyond the cuticle region, and toward the inside of the cortex region along with the disconnection of –SS– groups.     

The molecular interaction of Fas and FAP-1. A tripeptide blocker of human Fas interaction with FAP-1 promotes Fas-induced apoptosis

Fas (APO-1/CD95), which is a member of the tumor necrosis factor receptor superfamily, is a cell surface receptor that induces apoptosis. A protein tyrosine phosphatase, Fas-associated phosphatase-1 (FAP-1), that was previously identified as a Fas binding protein interacts with the C-terminal 15 amino acids of the regulatory domain of the Fas receptor. To identify the minimal region of the Fas C-terminal necessary for binding to FAP-1, we employed an in vitro inhibition assay of Fas/FAP-1 binding using a series of synthetic peptides as well as a screen of random peptide libraries by the yeast two-hybrid system. The results showed that the C-terminal three amino acids (SLV) of human Fas were necessary and sufficient for its interaction with the third PDZ (GLGF) domain of FAP-1. Furthermore, the direct cytoplasmic microinjection of this tripeptide (Ac-SLV) resulted in the induction of Fas-mediated apoptosis in a colon cancer cell line that expresses both Fas and FAP-1. Since t(S/T)X(V/L/I) motifs in the C termini of several other receptors have been shown to interact with PDZ domain in signal transducing molecules, this may represent a general motif for protein-protein interactions with important biological functions.     

Channelling studies on the lattice location of B atoms in graphite

In order to obtain information on the lattice location of B atoms in graphite, channelling experiments have been performed at room temperature with a proton beam of an energy of 0.65-0.77 MeV for the 〈0 0 0 1〉 axial channel in highly oriented pyrolytic graphite (HOPG) crystals doped with 0.32 at.% B. The B atoms are detected by measuring α-particles which are emitted as a result of a nuclear reaction ¹¹B(p,α)αα. It is clearly demonstrated that most of B atoms are shadowed behind the 〈0 0 0 1〉 C atomic rows. Taking account of the already reported experimental results on a change of lattice parameters by B-doping, it is concluded that most of B atoms are located at substitutional sites. It is also observed that B-doping introduces lattice strain on the c-plane. In addition, the presence of a small portion of interstitial B atoms is suggested.     

Discordant prolongation of the refractory period and repolarization time by a class III agent, E4031, in the healing phase of myocardial infarction

One hundred and ninety-eight adolescents and their mothers (N = 189) and fathers (N = 136) participated in a 4-year longitudinal study. Adolescent problem behaviour was assessed by the Youth Self-Report (YSR) and the Child Behavior Checklist (CBCL). In addition, parental stress and marital adjustment were determined. Results showed that mothers and fathers showed high agreement, especially about their daughters, whereas parents and adolescents showed little agreement. Agreement was higher for internalising than for externalising behaviours. In general, adolescents reported more symptomatology than their parents did. However, mothers' ratings of their children's behaviours were significantly correlated with adolescents' self-ratings, but fathers' ratings were not. Statistical tests of correlations showed that mothers experiencing stress caused by marital problems perceived more problem behaviours in their children. Fathers' perceptions were relatively unaffected by personal adjustment. However, poor marital adjustment perceived by both parents showed a significant negative relation to adolescent externalising problem behaviour.     

Age-related accumulation of phosphatidylcholine hydroperoxide in cultured human diploid cells and its prevention by α-tocopherol

The levels of phosphatidylcholine hydroperoxide in serially cultured human fetal diploid fibroblasts at various population doubling levels were determined by high-performance liquid chromatography combined with chemiluminescence detections. This methodology utilizes a mixture of cytochromec and luminol as post-column hydroperoxide group specific luminescent reagents. The cellular hydroperoxide content increased with age from 0.34 to 27.72 pmol/10⁶ cells. At the end of the cells'in vitro lifespan (51st population doubling level), the hydroperoxide content per 10⁶ cells reached about 80 times the level found in cells of the 20th population doubling level. Supplementation of exogenous α-tocopherol to the culture medium prevented hydroperoxide accumulation, but did not extent the lifespanin vitro. The results indicate that substantial intracellular phospholipid hydroperoxide accumulation occurred in the course of aging of human fetal liploid fibroblasts.     

Impregnation of silk sericin into polyester fibers using supercritical carbon dioxide

Silk sericin was impregnated into polyester fabric using supercritical carbon dioxide (SCCO₂) to overcome polyester hydrophobicity. The effects of sericin molecular weight, pH of sericin, solution and cosolvent types on sericin impregnation were investigated. Enzyme‐hydrolyzed, acid‐, based‐hydrolyzed sericin in SCCO₂, and a 30 kDa sericin in SCCO₂ modified with cosolvents such as water, methanol, 1‐propanol, and acetone; and a modifier: sodium hydroxide solution were used in this work. Impregnation of sericin in polyester was indicated by Fourier transform infrared spectrophotometry (FTIR) and dyeing with acid dye. Degradation of polyester fibers during SCCO₂ process was indicated by scanning electron microscopy (SEM). Methylene blue dyeing was used to realize carboxyl group in polyester. The results showed no impregnation of sericin into polyester by using SCCO₂ modified with cosolvents. However, sericin was impregnated into modified surface polyester since hydrophilic groups such as carboxyl and hydroxyl groups were regenerated by alkaline hydrolysis. Samples impregnated with hydrolyzed sericin showed high color strength of Supranolechtbordeaux B acid dye. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of SiC on Interfacial Reaction and Sintering Mechanism of TiB2

Compacts of TiB₂ with densities approaching 100% are difficult to obtain using pressureless sintering. The addition of SiC was very effective in improving the sinterability of TiB₂. The oxygen content of the raw TiB₂ powder used in this research was 1.5 wt%. X-ray photoelectron spectroscopy showed that the powder surface consisted mainly of TiO₂ and B₂O₃. Using vacuum sintering at 1700°C under 13–0.013 Pa, TiB₂ samples containing 2.5 wt% SiC achieved 96% of their theoretical density, and a density of 99% was achieved by HIPing. TEM observations revealed that SiC reacts to form an amorphous phase. TEM-EELS analysis indicated that the amorphous phase includes Si, O, and Ti, and X-ray diffraction showed the reaction to be TiO₂+ SiC → SiO₂+ TiC. Therefore, the improved sinterability of TiB₂ resulted from the SiO₂ liquid phase that was formed during sintering when the raw TiB₂ powder had 1.5 wt% oxygen.     

Separation and determination of glycolipids from edible plant sources by high-performance liquid chromatography and evaporative light-scattering detection

Glycolipids from edible plant sources were accurately quantified by silica-based, normal-phase high-performance liquid chromatography using an evaporative light-scattering detector. Five major glycolipid classes (acylated steryl glucoside, steryl glucoside, ceramide monohexoside, monogalactosyldiacylglycerol, and digalactosyldiacylglycerol) were separated and determined with a binary gradient system consisting of chloroform and methanol/water (95∶5, vol/vol) without any interference from other lipid classes and pigments. The described method was applied to 48 edible plants available in Japan including cereals, legumes, vegetables, and fruits. Examined plant species contained glycolipids in wide concentration ranges, such as 5–645 mg/100 g tissue.     

Autoxidation of ethyl eicosapentaenoate and docosahexaenoate

The extent of oxidation of ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) was compared quantitatively with that of ethyl linoleate (Lo) and ethyl linolenate (Ln) by oxygen uptake and formation of conjugated diene, hydroperoxide and secondary oxidation products. EPA and DHA esters were oxidized rapidly even at 5 C in the dark after an induction period of 3–4 days, while the induction periods of Ln and Lo esters were 20 days and more than 60 days, respectively. Oxygen uptake of EPA and DHA esters after the induction period was 5.2 and 8.5 times faster than that of ethyl Ln, respectively. Hydroperoxides of EPA and DHA esters are much less stable than those of ethyl Lo. The peroxide value is not necessarily a good indication of oxidation in these polyenoic acids because a considerable amount of secondary products is formed at the early stage of oxidation. Polymers were found to be major secondary products in these polyenoic esters.