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Biomedical subjects

Masahiro Suzuki

Publications and source records attributed to Masahiro Suzuki.

12 recordsLinked to original sources
PubMed2003

Design, synthesis, and evaluation of substituted phenylpropanoic acid derivatives as human peroxisome proliferator activated receptor activators. Discovery of potent and human peroxisome proliferator activated receptor alpha subtype-selective activators.

Substituted phenylpropanoic acid derivatives were prepared as part of a search for subtype-selective human peroxisome proliferator activated receptor alpha (PPARalpha) activators. Structure-activity relationship studies indicated that the nature and the stereochemistry of the substituent at the alpha-position of the head part containing the carboxyl group, the distance between the carboxyl group and the central benzene ring, the linking group between the central benzene ring and the distal benzene ring, and the substituent at the distal hydrophobic tail part of the molecule all play key roles in determining the potency and selectivity of PPAR subtype transactivation. This study has led to the identification of potent and human PPARalpha selective optically active alpha-alkylphenylpropanoic acid derivatives, which will be useful not only as pharmacological tools to investigate the physiology and pathophysiology of PPARalpha but also as candidate drugs for the treatment of altered metabolic homeostasis, such as dyslipidemia, obesity, and diabetes.

Animals↗
PubMed2003

A family of low-molecular-weight hydrogelators based on L-lysine derivatives with a positively charged terminal group.

A family of L-lysine-based low-molecular-weight compounds with various positively charged terminals (pyridinium and imidazolium derivatives) was synthesized and its gelation behavior in water was investigated. Most of the compounds can be very easily synthesized in high yields (total yields >90 %), and they function as excellent hydrogelators that form hydrogels below 1 wt %; particularly, N(epsilon)-lauroyl-N(alpha)-[11-(4-tert-butylpyridinium)undecanoyl]-L-lysine ethyl ester (2 c) and N(epsilon)-lauroyl-N(alpha)-[11-(4-phenylpyridinium)undecanoyl]-L-lysine ethyl ester (2 d), which are able to gel water at concentration of only 0.2 wt %. This corresponds to a gelator molecule that entraps more than 20 000 water molecules. All hydrogels are very stable and maintain the gel state for at least 9 months. TEM observations demonstrated that these hydrogelators self-assemble into a nanoscaled fibrous structure; a three-dimensional network is then formed by the entanglement of the nanofibers. An FTIR study in [D(6)]DMSO/D(2)O and in CHCl(3) revealed the existence of intermolecular hydrogen bonding between the amide groups. This was further supported by a (1)H NMR study in [D(6)]DMSO/H(2)O. A luminescence study, in which ANS (1-anilino-8-naphtharenesulfonic acid) was used as a probe, indicated that the hydrogelators self-assemble into nanostructures possessing hydrophobic pockets at a very low concentration. Consequently, it was found that the driving forces for self-assembly into a nanofiber are hydrogel bonding and hydrophobic interactions.

Gels↗
PubMed2003

Leonardo's constraint: two opaque objects cannot be seen in the same direction.

Given Leonardo's constraint that 2 opaque objects cannot be seen in the same direction, how are the regions of objects occluded to 1 eye included in perception? To answer this question, the authors presented 3-dimensional stimuli, similar to the ones that concerned Leonardo, and measured the visual directions of their monocular and binocular regions. When the distance between near and far objects was large, the nonfixated object was seen as double and blurry. Leonardo's constraint was met by seeing the near object as double and transparent or the distant object as double and superimposed. When the distance between near and far objects was small, the constraint was met by a perceptual displacement and compression of parts of the nonfixated object.

Depth Perception↗
PubMed2002

Preparation of helical transition-metal oxide tubes using organogelators as structure-directing agents.

We prepared novel transition-metal (Ti, Ta, V) oxide fibers with chiral, helical, and nanotubular structures. The nanostructured metal oxide materials were provided by the sol-gel polymerization of metal alkoxides using chiral self-assemblies of organogelators as structure-directing agents. The chiral structures of the metal oxide fibers can be created by the formation of chiral self-assemblies constructed by organogelators and the transcription of the organogel superstructure into metal oxides.

Journal Article↗
PubMed2002

Enantio-dependent binding and transactivation of optically active phenylpropanoic acid derivatives at human peroxisome proliferator-activated receptor alpha.

Optically active phenylpropanoic acid derivatives [(S)-5, and (R)-5] were prepared, and their affinities for peroxisome proliferator-activated receptor (PPAR)alpha and PPAR gamma were evaluated. Binding assay and cell-based reporter assay indicated that the activity of these compounds is enantio-dependent, and resides exclusively on the (S)-isomer.

Crystallography, X-Ray↗
PubMed2002

Suppression of fruit-body formation by constitutively active G-protein alpha-subunits ScGP-A and ScGP-C in the homobasidiomycete Schizophyllum commune.

The heterotrimeric G-protein alpha-subunit family plays multiple roles in eukaryotic cells, such as the regulation of growth and development, of pathogenicity and of the transmission of pheromone stimulation. In the homobasidiomycete Schizophyllum commune, some genes encoding heterotrimeric G-protein alpha-subunits (SCGPalpha1, SCGPalpha2, ScGP-A, ScGP-B and ScGP-C) have been reported. In this study, constitutively active mutants of ScGP-A, ScGP-B and ScGP-C were generated by site-directed mutagenesis and introduced into the S. commune monokaryon strain to investigate the function of each gene. Northern analysis showed that the mutated genes were strongly expressed when compared with endogenous G-proteins in many clones. Upon macroscopic examination, some transformed clones expressing ScGP-A (Q207R) and ScGP-C (Q204R) mutant genes exhibited a slight suppression of aerial-hyphae formation in the monokaryon strain. In contrast to the slight suppression of aerial-hyphae formation in the monokaryon, most clones expressing mutated ScGP-A or ScGP-C genes failed to form fruit-bodies in the dikaryon strain. This observation indicated that ScGP-A and ScGP-C played a role in suppressing fruit-body formation in the dikaryon. Furthermore, these phenotypes were similar to the phenotype of the thn mutant in S. commune to some extent. Since the thn-1 gene encodes a putative regulator of the G-protein signalling protein (RGS), ScGP-A and ScGP-C might be targets of thn-1.

Amino Acid Sequence↗
PubMed2002

Optical resolution by preferential crystallization of (RS)-2-benzoylamino-2-benzyl-3-hydroxypropanoic acid and its use in synthesizing optically active 2-amino-2-methyl-3-phenylpropanoic acid.

To synthesize optically active 2-amino-2-methyl-3-phenylpropanoic acid (1), (RS)-2-benzoylamino-2-benzyl-3-hydroxypropanoic acid [(RS)-2] was first optically resolved using cinchonidine as a resolving agent to yield optically pure (S)- and (R)-2 in yields of about 70%, based on half of the starting amount of (RS)-2. Next, the racemic structure of (RS)-2 was examined based on melting point, solubility, IR spectrum, and binary and ternary phase diagrams, with the aim of optical resolution by preferential crystallization of (RS)-2. Results indicated that the (RS)-2 exists as a conglomerate at room temperature, although it forms a racemic compound at the melting point. The optical resolution by preferential crystallization yielded (S)- and (R)-2 with optical purities of about 90%, which were fully purified by recrystallization. After O-tosylation of (S)- and (R)-2, reduction by zinc powder and sodium iodide gave (R)- and (S)-1, respectively.

Crystallization↗
PubMed2002

[Binocular rivalry in half-occluded region is weakened by eye movement].

To investigate the effect of eye movement on suppression of binocular rivalry in the half-occluded region, which is the monocular region made by occlusion, the amount of binocular rivalry in the half-occluded region was measured in the eye movement condition and the fixating condition. In the eye movement condition, the observer moved their eyes between the occluder and the occluded object. In the fixating condition, the observers fixated the occluder (the fixating-the-occluder condition) or the occluded object (the fixating-the-occluded-object condition). Following facts were found: (a) the amount of binocular rivalry in the half-occluded region reduced more in the eye movement condition than in the two fixating conditions, (b) there was no significant difference in the amount of binocular rivalry in the half-occluded region between the two fixating conditions. These results suggested that eye movement is one of the factors to suppress binocular rivalry in the half-occluded region in natural viewing situations.

Eye Movements↗
PubMedDate not supplied

Effects of weight reduction on neutrophil phagocytic activity and oxidative burst activity in female judoists.

This study investigated the effects of short-term weight reduction on neutrophil functions in female judoists. Sixteen actively competing female judoists were divided into two groups. Eight who required weight reduction were defined as the weight reduction group, and the remaining eight were used as the control. Blood samples were taken before, immediately after and 8 days after the match. Phagocytic activity and oxidative burst activity of neutrophils were measured by flow cytometry. In the weight reduction group, the phagocytic activity per cell decreased significantly at the end of weight reduction compared with the control group. The rate of neutrophils producing reactive oxygen species and the oxidative burst activity per cell increased significantly at the end of weight reduction in both the control and the weight reduction groups. We concluded that weight reduction, consisting of both intense exercise and energy restriction, might possibly cause both an increase in oxidative burst activity and decrease in neutrophil phagocytic activity in female judoists. However, although exercise increased oxidative burst activity, it did not affect neutrophil phagocytic activity alone. Therefore, to avoid this problem, female judoists are recommended to keep their weight within those limits determined by their class, and which can be reduced by exercise.

Blood Cell Count↗