A peptide carrying a mercaptomethylated proline derivative at the C-terminus was prepared by solid-phase peptide synthesis (SPPS) and converted to the thioester of 3-mercaptopropionic acid (MPA) by aqueous MPA under microwave irradiation conditions. This post-SPPS thioesterification reaction was successfully applied to the synthesis of a glycopeptide thioester composed of 25 amino acid (AA) residues, which was then used for the preparation of a 61-AA glycopeptide by the thioester condensation method.

A thermo-responsive elastin, elastin-like peptide (ELP)-gold nanoparticle (AuNP) hybrid (ELP-AuNP), was successfully prepared via the in situ reduction of HAuCl 4 in the presence of lipoic acid-terminated ELP: (VPGVG) 4 (V:valine, P:proline, G:glycine) synthesized using a solid-phase peptide synthesis method. The conformation and aggregation properties of the ELP-AuNP in an aqueous buffer solution were examined using circular dichroism (CD) and ultraviolet-visible (UV-Vis) spectroscopies and transmission electron microscopy (TEM) observation. The phase transition of the ELP layer at the periphery of the AuNP because of the conformational change from random coil to b-turn structures was found to proceed gradually with increasing temperature and to simultaneously cause an aggregation of the ELP-AuNP because of the component's hydrophobic interactions and a color change of the solutions from red to violet. The ELP-AuNPs were aligned selectively onto patterned, hydrophobic polystyrene stripes on a glass plate when the plate was immersed and incubated in the solution containing the ELP-AuNP above its phase transition temperature, as verified using atomic force microscopy (AFM) and scanning electron microscopy (SEM).

Incubation of hepatocarcinogenic aminoazo dye, o-aminoazotoluene (OAT) with rat liver microsomes together with NADPH and NADH yielded N-hydroxy-OAT (I), 4'-hydroxy-OAT (II) and a smaller amount of 2'-hydroxymethyl-3-methyl-4-aminoazobenzene (III). As an artifact 4,4'-bis(o-tolylazo)-2,2' -dimethylazoxybenzene (IV) was also detected in a small quantity. The mutagenicities of these metabolites were assayed by using Salmonella typhimurium TA98 and TA100 together with S-9 prepared from the livers of rats treated with polychlorinated biphenyl mixture (PCB). OAT and III were strongly mutagenic, but only when S-9 was present. In contrast, I was a strong mutagen regardless of the presence or absence of S-9. II and IV were non-mutagenic. The yields of I, II and III from OAT were pronouncedly reduced by addition of cytochrome P-450 inhibitors, especially by a cytochrome P-448 inhibitor 7,8-benzoflavone. Mutagenesis by OAT was also inhibited by addition of 7,8-benzoflavone. Activation of OAT for mutagenesis was enhanced by pretreatment of the donor rats with PCB or 3-methyl-cholanthrene and to a much lesser extent by phenobarbital. These findings suggest that N-hydroxylation of OAT mainly proceeds via catalysis by cytochrome P-448 and that this process is an obligatory step for the activation of OAT. Synthetic methods for the preparation of new azo compounds such as I, IV and 2',3-dimethyl-4-nitrosoazobenzene are described.

This study used an ultrasonic measurement device to monitor the setting behavior of silicone elastomeric impression materials, and the influence of temperature on setting behavior was determined. The ultrasonic device consisted of a pulser-receiver, transducers, and an oscilloscope. The two-way transit time through the mixing material was divided by two to account for the down-and-back travel path; then it was multiplied by the sonic velocity. Analysis of variance and the Tukey honest significant difference test were used. In the early stages of the setting process, most of the ultrasonic energy was absorbed by the elastomers and the second echoes were relatively weak. As the elastomers hardened, the sonic velocities increased until they plateaued. The changes in sonic velocities varied among the elastomers tested, and were affected by temperature conditions. The ultrasonic method used in this study has considerable potential for determining the setting processes of elastomeric impression materials.