[Non-electrocardiogram-gated and Non-contrast-enhanced Magnetic Resonance Angiography of the Lower Limb Arteries Using Three-dimensional Multishot T1-weighted Fast-field Echo-Echo Planar Imaging].

We performed a non-electrocardiogram-gated and non-contrast-enhanced magnetic resonance angiography (MRA) of the lower limb arteries using three-dimensional multishot T1-weighted fast-field echo-echo planar imaging (3D multishot T1-FFE-EPI), and it was optimized the protocol. The image distortion for the change in the EPI factor was calculated using 3.0 T-MRI and MRI phantom. We also calculated the signal-to-noise ratio (SNR) of the femoral artery with a change in the flip angle on images of 8 healthy volunteers. Furthermore, the optimal EPI factor was determined from the SNR of the femoral artery and the contrast ratio between the femoral artery and the adductor magnus. Two radiological technologists performed a retrospective visual assessment of the pelvis, thigh, and leg of 10 patients who underwent lower limb non-contrast-enhanced MRA and contrast-enhanced tomography angiography (CTA). The optimum flip angle and EPI factor were 25° and 3, respectively. In the visual assessment of clinical cases, there was no significant difference between the non-contrast-enhanced MRA and contrast-enhanced CTA in the pelvis and the leg (p=0.52 and p=0.88, respectively). In the thigh, non-contrast-enhanced MRA was significantly higher (p=0.02), namely, the ability to visualize the lower limb arteries was not much difference between this method and contrast-enhanced CTA. Our method without electrocardiogram gated and contrast medium is expected for screening tests or detailed examinations.

Synthesis and anticancer activity of bis(2-arylimidazo[1,2-a]pyridin-3-yl) selenides and diselenides: the copper-catalyzed tandem C-H selenation of 2-arylimidazo[1,2-a]pyridine with selenium.

Most heteroaryl selenides and diselenides are biologically active, with some reported to act as antioxidants and show activities that are medicinally relevant; hence, the development of efficient methods for their synthesis is an important objective. Herein, a simple method for the synthesis of selenides and diselenides bearing imidazo[1,2-a]pyridine rings and their anticancer activity are described. The double C-H selenation of imidazo[1,2-a]pyridine with Se powder was catalyzed by CuI (10 mol %) ligated with 1,10-phenanthroline (10 mol %) at 130 °C under aerobic conditions. The selenides or diselenides were prepared almost selectively using selenium powder in an appropriate quantity under otherwise identical reaction conditions. The prepared selenides and diselenides bearing two imidazo[1,2-a]pyridine rings were all novel compounds. Among the prepared diselenides and selenides that exhibited cytotoxicity against cancer cells, bis[2-(4-methoxyphenyl)imidazo[1,2-a]pyridin-3-yl] diselenide showed an excellent anticancer activity and low cytotoxicity toward noncancer cells, suggesting that this diselenide is a potential lead compound for anticancer therapy.

Crystalline sponge-laser desorption ionization (CS-LDI) of unsaturated cyclic organic compounds encapsulated in different electronic environments in pores.

We have developed laser desorption ionization mass spectrometry (LDI-MS) of organic molecules encapsulated in a crystalline sponge (CS). Cyclic organic compounds 1,2,3,4,5-pentamethylcyclopentadiene, zerumbone, and muscone were encapsulated in CS as guest regardless of guest crystallization. Single-crystal X-ray analysis closely scrutinized the position of the guest in the pore and the interaction between the guest and the CS framework. After single-crystal X-ray analysis, the same single crystal was subjected to LDI-MS. Ionization efficiency differed markedly depending on whether π-π interaction existed or not. It is obvious that π-π interaction is the key to transferring laser energy from the CS framework to the guest for the ionization of molecule encapsulated in CS. The results suggest the importance of controlling the positions of analyte and matrix as well as noncovalent interactions, such as hydrogen bonding interaction, electrostatic interaction, and so on.

Tolerance of bitter stimuli and attenuation/accumulation of their bitterness in humans.

Some components of bitterness make key flavor contributions to promote the palatability of foods, whereas other components are recognized as aversive signals to avoid consuming harmful substances. These contradictory behaviors suggest that humans tolerate tastes of bitterants based on certain criteria. Here, we investigated human taste tolerance and sensory cues leading to diverse taste tolerance of bitter compounds. Tolerance of eight bitter compounds, which are typically contained in foods, was evaluated by measuring detection and rejection thresholds. The results revealed that the level of tolerance of each compound was variable, and some compounds showed an acceptable concentration regarding the suprathreshold intensity. Tolerance did not depend on the nutritive value or attenuation and accumulation characteristics of bitterness and bitter taste receptors. These results suggest that the criteria controlling tolerance of bitter compounds may be derived from a complex relationship between the taste quality and cognitive process.

Combined analysis of 1,3-benzodioxoles by crystalline sponge X-ray crystallography and laser desorption ionization mass spectrometry.

The crystalline sponge (CS) method, which employs single-crystal X-ray diffraction to determine the structure of an analyte present as a liquid or an oil and having a low melting point, was used in combination with laser desorption ionization mass spectrometry (LDI-MS). 1,3-Benzodioxole derivatives were encapsulated in CS and their structures were determined by combining X-ray crystallography and MS. After the X-ray analysis, the CS was subjected to imaging mass spectrometry (IMS) with an LDI spiral-time-of-flight mass spectrometer (TOF-MS). The ion detection area matched the microscopic image of the encapsulated CS. In addition, the accumulated 1D mass spectra showed that fragmentation of the guest molecule (hereafter, guest) can be easily visualized without any interference from the fragment ions of CS except for two strong ion peaks derived from the tridentate ligand TPT (2,4,6-tris(4-pyridyl)-1,3,5-triazine) of the CS and its fragment. X-ray analysis clearly showed the presence of the guest as well as the π-π, CH-halogen, and CH-O interactions between the guest and the CS framework. However, some guests remained randomly diffused in the nanopores of CS. In addition, the detection limit was less than sub-pmol order based on the weight and density of CS determined by X-ray analysis. Spectroscopic data, such as UV-vis and NMR, also supported the encapsulation of the guest through the interaction between the guest and CS components. The results denote that the CS-LDI-MS method, which combines CS, X-ray analysis and LDI-MS, is effective for structure determination.

Diversity of γ- glutamyl peptides and oligosaccharides, the "kokumi" taste enhancers, in seeds from soybean mini core collections.

Soybeans (Glycine max (L,) Merr,) contain γ-glutamyl peptides and oligosaccharides, and these components play an important role in imparting the "kokumi" taste to foods. To gain insight into the genetic diversities and molecular mechanisms of accumulation of γ-glutamyl peptides and oligosaccharides in soybean, we measured the contents of these components using the Japan and World mini core collections. Similar to other previously reported traits, wide variations were detected among the accessions in the core collections with respect to the content of γ-glutamyl peptides and oligosaccharides. We found a positive relationship between the content of γ-glutamyl tyrosine and γ-glutamyl phenylalanine and between the content of raffinose and stachyose. Furthermore, there were unique accessions that included high levels of γ-glutamyl peptides and oligosaccharides. These accessions may be helpful in understanding the accumulation mechanism of γ-glutamyl peptides and oligosaccharides and to increase the "kokumi" taste components in soybean by performing a genetic analysis.

Innate and acquired tolerance to bitter stimuli in mice.

Tolerance to bitter foods and its potentiation by repetitive exposure are commonly experienced and potentially underlie the consumption of bitter foods, but it remains unknown whether permissive and adaptive responses are general phenomena for bitter-tasting substances or specific to certain substances, and they have not been rigorously studied in mice. Here, we investigated the effects of prolonged exposure to a bitter compound on both recognition and rejection behaviors to the same compound in mice. Paired measurements of rejection (RjT) and apparent recognition (aRcT) thresholds were conducted using brief-access two-bottle choice tests before and after taste aversion conditioning, respectively. First, RjT was much higher than aRcT for the bitter amino acids L-tryptophan and L-isoleucine, which mice taste daily in their food, indicating strong acceptance of those familiar stimuli within the concentration range between RjT and aRcT. Next, we tested five other structurally dissimilar bitter compounds, to which mice were naive at the beginning of experiments: denatonium benzoate, quinine-HCl, caffeine, salicin, and epigallocatechin gallate. RjT was moderately higher than aRcT for all the compounds tested, indicating the presence of innate acceptance to these various, unfamiliar bitter stimuli in mice. Lastly, a 3-week forced exposure increased RjT for all the bitter compounds except salicin, demonstrating that mice acquire tolerance to a broad array of bitter compounds after long-term exposure to them. Although the underlying mechanisms remain to be determined, our studies provide behavioral evidence of innate and acquired tolerance to various bitter stimuli in mice, suggesting its generality among bitterants.

Isolation and characterization of key contributors to the "kokumi" taste in soybean seeds.

The water extract of soybean seeds (Glycine max (L.) Merr.) is nearly tasteless, but "kokumi" taste sensation was confirmed upon addition of a basic umami solution containing glutamic acid, inosine monophosphate, and sodium chloride. To identify the key contributors to the "kokumi" taste sensation in soybean seeds, sensory-guided fractionation, taste sensory analyses, and LC-MS/MS analyses were utilized. γ-glutamyl-tyrosine and γ-glutamyl-phenylalanine were identified as contributors to "kokumi taste"; specifically, these γ-glutamyl peptides imparted the "kokumi" taste sensation at a low taste threshold in a basic umami solution. Raffinose and stachyose, which are sufficiently present in soybean seeds, exhibited a synergistic effect in regard to the enhanced "kokumi" taste sensation of γ-glutamyl peptides. This is the first report that the combined use of γ-glutamyl peptides and oligosaccharides can increase the "kokumi" intensity, which suggests that soybean extracts or soymilk can be used to enhance the "kokumi" taste sensation in food products.

L-Theanine elicits umami taste via the T1R1 + T1R3 umami taste receptor.

L-Theanine is a unique amino acid present in green tea. It elicits umami taste and has a considerable effect on tea taste and quality. We investigated L-theanine activity on the T1R1 + T1R3 umami taste receptor. L-Theanine activated T1R1 + T1R3-expressing cells and showed a synergistic response with inosine 5'-monophosphate. The site-directed mutagenesis analysis revealed that L-theanine binds to L-amino acid binding site in the Venus flytrap domain of T1R1. This study shows that L-theanine elicits an umami taste via T1R1 + T1R3.

Evaluation of the suppressive effect on bitter taste of gluconate.

Gluconate is used as an additive in a wide range of processed foods. In this study, we investigated its utility as a taste-improving substance. To determine whether it has a suppressive effect on bitter taste, sensory evaluations were performed by human subjects. When gluconate was added to a quinine-HCl (QHCl) solution, the taste intensity decreased, but this effect was not observed when it was added to caffeine and to naringin solutions. Then we investigated the mechanism of suppression by performing behavioral and electrophysiological assays on mice. In mice, the addition of gluconate improved the taste preference for and reduced the gustatory nerve response to QHCl. In sum, gluconate had a suppressive effect on the bitter taste of QHCl, which might have been caused by depression of gustatory nerve activity.

Nerve and behavioral responses of mice to various umami substances.

Food contains various taste substances. Among them, umami substances play an important role with regard to the perception of the taste of food, but, few studies have examined the taste characteristics of representative umami substances other than monosodium L-glutamate (MSG). By conducting mouse behavioral studies (the 48-h 2-bottle preference test and the conditioned taste aversion test) and assessing gustatory nerve responses, we investigated the taste characteristics of unique umami substances, including sodium succinate, L-theanine, betaine, and the enantiomer of MSG, D-MSG. Furthermore, we examined the synergy of umami with inosine 5'-monophoshate (IMP). In the case of the mice, sodium succinate had an umami taste and showed strong synergy with IMP. L-theanine showed synergy with IMP but did not have an umami taste without IMP. In contrast, betaine did not have an umami taste or synergy with IMP. D-MSG might have weak synergy with IMP.

Supplementation with a flavanol-rich lychee fruit extract influences the inflammatory status of young athletes.

Flavanol-rich lychee fruit extract (FRLFE) is a processed lychee fruit extract that is higher in flavanols (monomers, dimers and trimers) than its unprocessed counterpart. FRLFE exerts antioxidant activities in vitro and is expected to protect against inflammation and tissue damage. However, the physiological effects of FRLFE intake have not been explored in vivo. The aim of this study was to examine the effects of FRLFE supplementation on inflammation and tissue damage in young athletes during intense physical training. Twenty healthy male long-distance runners at a university were randomly assigned to receive FRLFE or placebo in a double-blind manner. Blood and serum parameters associated with inflammation, tissue damage and oxidative stress were evaluated before (pre-training), during (mid-training) and after (post-training) a 2-month training period. Some parameters, including the white blood cell count, were significantly modified by FRLFE supplementation. Compared with the placebo group, the change in the serum interleukin-6 level between pre- and mid-training were significantly lower in the FRLFE group, while the change in the transforming growth factor-ß level between pre- and post-training was significantly greater in the FRLFE group. These findings suggest that FRLFE supplementation may suppress inflammation or tissue damage caused by high-intensity exercise training.

Development of a compact system for the determination of lead using a liquid core waveguide and a blue diode as a light source.

A simple and compact system was developed for the on-site analysis of lead in environmental water samples. The system consisted of a custom-made blue diode as a light source, a liquid core waveguide (LCW) as spectrophotometric cell and a compact UV-visible spectrometer. It weighed within 1.5 kg in total. Lead was detected using a spectrophotometric indicator reagent (TPPS: 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid, disulfuric acid, tetrahydrate) after masking interfering ions by coprecipitation with magnesium hydroxide. With an increase in the length of the LCW cell, the detection limit of lead was almost linearly enhanced, and the linear calibration range was shifted to a lower concentration range. The detection limit of lead by using 100 cm of a LCW cell was 2 nmol dm(-3). The observed value (9.6 +/- 0.4 microg dm(-3)) of lead in a river-water reference material (JSAC 0302-3) with this system was in good agreement with the certified value (9.9 +/- 0.2 microg dm(-3)).

An amperometric D-amino acid biosensor prepared with a thermostable D-proline dehydrogenase and a carbon nanotube-ionic liquid gel.

Carbon nanotube (CNT) gel, which is composed of a mixture of single-wall CNT, an ionic liquid, and a thermostable D-proline dehydrogenase (D-Pro DH) immobilized electrode was utilized for the determination of D-amino acids (DAAs) in food samples. When a critical comparison with CNT, Ketjen Black (KB), and carbon powder (CP) was also carried out, the CNT/D-Pro DH immobilized electrode showed the highest sensitivity and the lowest detection limit of D-proline. In addition, the CNT/D-Pro DH immobilized electrode was applied to detection of DAAs in rice wine and vinegar samples. The concentrations of DAAs in rice wine and vinegar samples were 0.0210 +/- 0.0001 and 0.55 +/- 0.05 mmol L(-1), respectively.

Signalling mechanisms in mouse bitter responsive taste cells.

To clarify the components involved in mouse intracellular bitter transduction in the mouse, we investigated the expression patterns of transduction components and the contribution of intracellular Ca2+ stores. Of 64 cells responding to bitter compounds, 63% of the cells expressed the taste tissue-specific G-protein alpha-gustducin. Of the alpha-gustducin immunoreactive cells, 78% expressed IP3R3, a receptor that mediates Ca2+ release from the intracellular store. When intracellular Ca2+ was depleted by treatment with the inhibitor thapsigargin, 83% of the taste cells lost their response to bitter. These data suggest that bitterness transduction involves the release of Ca2+ from intracellular stores.

L-theanine elicits an umami taste with inosine 5'-monophosphate.

We investigated the taste synergy between L-theanine and the flavour enhancer, inosine 5'-monophosphate (IMP), by using a human sensory evaluation. When L-theanine was added to IMP, only the umami taste was enhanced. We then investigated this synergistic effect of L-theanine in mice by gustatory nerve recording. We confirmed the synergism between L-theanine and IMP for the umami taste.

Characterization of umami receptor and coupling G protein in mouse taste cells.

Taste receptor cells (TRCs) express multiple umami receptors. We performed physiological investigations to determine whether umami-responding cells in taste buds possess G protein-coupled receptors and to determine what type of G proteins exist if any. To clarify the components that participate in intracellular umami signal transduction in mouse, we recorded the activation of TRCs. TRCs treated with the G protein inhibitor GDP-beta-S lost umami-induced inward currents. Treatment with the Galphai inhibitor, pertussis toxin, did not increase the intracellular Ca2+ level in many TRCs. Immunohistochemical analysis revealed that a subset of TRCs responding to umami stimuli expressed alpha-gustducin. Thus, we demonstrated that umami stimuli were received by G protein-coupled receptors that function together with some of the Galphai family members.

Umami changes intracellular Ca2+ levels using intracellular and extracellular sources in mouse taste receptor cells.

Recently, candidates for umami receptors have been identified in taste cells, but the precise transduction mechanisms of the downstream receptor remain unknown. To investigate how intracellular Ca(2+) increases in the umami transduction pathway, we measured changes in intracellular Ca(2+) levels in response to umami stimuli monosodium glutamate (MSG), IMP, and MSG + IMP in mouse taste receptor cells (TRCs) by Ca(2+) imaging. Even when extracellular Ca(2+) was absent, 1/3 of umami-responsive TRCs exhibited increased intracellular Ca(2+) levels. When intracellular Ca(2+) was depleted, half of the TRCs retained their response to umami. These results suggest that umami-responsive TRCs increase their intracellular Ca(2+) levels through two pathways: by releasing Ca(2+) from intracellular stores and by an influx of Ca(2+) from extracellular sources. We conclude that the Ca(2+) influx from extracellular source might play an important role in the synergistic effect between MSG and IMP.

G-protein-dependent and -independent pathways in denatonium signal transduction.

To clarify the involvement of G protein in denatonium signal transduction, we carried out a whole-cell patch-clamp analysis with isolated taste cells in mice. Two different responses were observed by applying GDP-beta-S, a G-protein inhibitor. One response to denatonium was reduced by GDP-beta-S (G-protein-dependent), whereas the other was not affected (G-protein-independent). These different patterns were also observed by concurrently inhibiting the phospholipase C beta2 and phosphodiesterase pathways via G protein. These data suggest dual, G-protein-dependent and -independent mechanisms for denatonium. Moreover, the denatonium responses were not attenuated by singly inhibiting the phospholipase C beta2 or phosphodiesterase pathway, implying that both pathways were involved in G-protein-dependent transduction. In the G-protein-independent cells, the response was abolished by the depletion of calcium ions within the intracellular store. These results suggest that Ca2+ release from the intracellular store is an important factor. Our data demonstrate multiple transduction pathways for denatonium in mammalian taste cells.