代謝性疾病リスク低減への応用を目指した食品成分の機能解析

学位の種別: 論文博士審査委員会委員 : （主査）東京大学教授 佐藤 隆一郎, 東京大学特任教授 朝倉 富子, 東京大学准教授 戸塚 護, 東京大学准教授 三坂 巧, 東京大学准教授 井上 順University of Tokyo(東京大学

Components Associated With Saltiness Potentiation in Frankfurters Made With Traditionally Brewed Soy Sauce

Salt is a critical ingredient in processed meat and poultry products because of its multiple functions that affect product quality and safety. Although salt is a functional ingredient in food products, sodium reduction continues to be an important topic within the food industry due to interests in reducing dietary sodium intake. Previous work has shown that soy sauce addition may potentiate saltiness perception in processed meats and thus allow for novel formulations with reduced sodium content. Two studies were conducted to further elucidate these effects. First, trained panel sensory char- acteristics, relevant quality parameters, and selected chemical profiles were determined comparing frankfurters containing flake salt and traditionally brewed soy sauce. Seven aqueous compounds were found to be more abundant (P < 0.001) in the soy sauce – containing treatment, and 56 volatile compounds were identified. Principal component analysis of the sensory and selected chemical profiles led to the consideration that ethyl hexanoate (EHEX) may be a causative agent of the saltiness-potentiating phenomenon. Thus, a second study further evaluated concentrations of EHEX, revealing that trained sensory panelists perceived frankfurters containing EHEX as saltier (P < 0.05) and these frankfurters had higher scores for fermented/sour aromatic score (P < 0.05) than the control (Control: 100% NaCl from flake salt). This research demon- strated the ability of EHEX to potentiate saltiness in frankfurters with minimal effects on quality

Metabolomic Biomarkers Differentiate Soy Sauce Freshness under Conditions of Accelerated Storage

Naturally fermented soy sauce is one of the few globally valued food condiments. It is complex in its substrate, manufacturing processes, and chemical profile of salts and organic compounds, resulting from spontaneous, enzymatic and biochemical reactions. The overall chemical character of soy sauce has a few rivals relative to its chemical and bioactive complexity. Resulting from this complexity are unique sensory attributes contributing to the characteristic soy sauce flavor as well as potentiating other sensory sensations. Soy sauce is susceptible to deterioration after bottling during storage. This work examined soy sauces over an eight-month period using descriptive sensory methods and the discovery of metabolomic biomarkers with high resolution mass spectrometry, wherein samples were derivatized to enable volatility and identification of polar analytes. While several thousand metabolites were detected, only organic acids, amino acids, and various glycosylated metabolites were statistically defensible biomarkers of storage time. The relationships between sensory and metabolomic data were assessed using Kendall rank-based correlations to generate Kendall Tau correlation coefficients. A second approach filtered the data based on correlation significance and grouped molecules based on hierarchical clustering. Mass spectrometry analyses discovered several thousand unique analyte peaks with relevant changes denoted as significant relative to the fresh samples using volcano depictions of p values versus changes in compound abundances. We present a metabolomic approach for the analysis of complex food systems capable of differentiating a quantifiable extrinsic variable, which is, in this case, storage time with a correlation coefficient of 0.99. We further demonstrate that changes in soy sauce resulting from storage are characterized by sensory decreases in fruity/grape and nutty/sesame aroma and increases in methional/potato aroma and astringent attributes with concomitant changes in the concentrations of several key biomarkers

Polarity reversal of the charge carrier in tetragonal TiH_{x}(x=1.6−2.0) at low temperatures

We present a combined experimental and theoretical study of the charge transport properties of TiH_{x}(x=1.6–2.0) epitaxial thin films. We found that the Hall coefficient of TiH_{x} strongly depends on hydrogen content and unit-cell volume: Nearly stoichiometric TiH_{x}(x≈2.0) films with large unit-cell volumes showed positive Hall coefficients at 4 K, whereas TiH_{x} samples with x<∼1.7 and small unit-cell volumes showed negative Hall coefficients at 4 K. Our density functional theory calculations reveal that the volume change leads to the change in the aspect ratio of the tetragonal lattice, thereby lifting the degeneracy of Ti t_{2g} states, and alters the contributions of electrons and holes at the Fermi surface and the sign of the Hall coefficient. The present study clarifies the important role of the lattice symmetry in determining the charge carrier polarity, and we suggest that electronic properties of metal hydrides can be tuned by the lattice parameters via the hydrogen contents

Evaluation of lower extremity gait analysis using Kinect V2

Introduction: Microsoft Kinect V2® (Kinect) is a peripheral device of Xbox® and acquires information such as depth, posture, and skeleton definition. In this study, we investigated whether Kinect can be used for human gait analysis. Methods: Ten healthy volunteers walked 20 trials, and each walk was recorded by a Kinect and infrared- and marker-based-motion capture system. Pearson’s correlation and overall agreement with a method of meta-analysis of Pearson’s correlation coefficient were used to assess the reliability of each parameter, including gait velocity, gait cycle time, step length, hip and knee joint angle, ground contact time of foot, and max ankle velocity. Hip and knee angles in one gait cycle were calculated in Kinect and motion capture groups. Results: The coefficients of correlation for gait velocity (r = 0.92), step length (r = 0.81) were regarded as strong reliability. Gait cycle time (r = 0.65), minimum flexion angle of hip joint (r = 0.68) were regarded as moderate reliability. The maximum flexion angle of the hip joint (r = 0.43) and maximum flexion angle of the knee joint (r = 0.54) were regarded as fair reliability. Minimum flexion angle of knee joint (r = 0.23), ground contact time of foot (r = 0.23), and maximum ankle velocity (r = 0.22) were regarded as poor reliability. The method of meta-analysis revealed that participants with small hip and knee flexion angles tended to have poor correlations in maximum flexion angle of hip and knee joints. Similar trajectories of hip and knee angles were observed in Kinect and motion capture groups. Conclusions: Our results strongly suggest that Kinect could be a reliable device for evaluating gait parameters, including gait velocity, gait cycle time, step length, minimum flexion angle of the hip joint, and maximum flexion angle of the knee joint

Growth Factor-induced Phosphorylation of Sterol Regulatory Element-binding Proteins Inhibits Sumoylation, Thereby Stimulating the Expression of Their Target Genes, Low Density Lipoprotein Uptake, and Lipid Synthesis*S⃞

The destiny and activity of sterol regulatory element-binding proteins (SREBPs) in the nucleus are regulated by modification with ubiquitin, small ubiquitin-like modifier (SUMO), or phosphorus. ERK-dependent phosphorylation causes an increase in their transcriptional activity, whereas SUMO modification halts it. We hypothesized a causal linkage between phosphorylation and sumoylation because their sites are very closely located in SREBP-1 and -2 molecules. When Ser455, a phosphorylation site in SREBP-2, was substituted with Ala, this SREBP-2 mutant was more efficiently modified by SUMO-1. On the other hand, substitution of Asp inhibited SUMO conjugation, mimicking phosphoserine. When cells were cultured with insulin-like growth factor-1, sumoylation of SREBP-2 was decreased with an increase in its phosphorylation, but SREBP-2(S455A) was continuously sumoylated. An ERK cascade inhibitor, U0126, inversely augmented SUMO modification of SREBP-2. Insulin-like growth factor-1 treatment stimulated the expression of SREBP target genes such as the low density lipoprotein (LDL) receptor, squalene synthase, and hydroxymethylglutaryl-CoA synthase genes. These results indicate that growth factor-induced phosphorylation of SREBP-2 inhibits sumoylation, thereby facilitating SREBP transcriptional activity. Glutathione S-transferase pulldown assays revealed that wild-type SREBP-2, but not a mutant lacking Lys464, interacts with HDAC3 preferentially among the histone deacetylase family members. HDAC3 small interfering RNA induced gene expression of the LDL receptor and thereby augmented fluorescently labeled LDL uptake in HepG2 cells. In summary, growth factors inhibit sumoylation of SREBPs through their phosphorylation, thus avoiding the recruitment of an HDAC3 corepressor complex and stimulating the lipid uptake and synthesis required for cell growth