Biomedical subjects
Publications and source records attributed to Hideki Masuda.
A mononuclear copper(II)-hydroperoxo species has been generated by the reaction of Cu(I)-H2BPPA complex with dioxygen, which illustrates the enzymatic reaction process of the CuB site in the DbetaM and PHM.
Three saponins, isotheasaponins B1-B3, were isolated from the leaves of the tea plant Camellia sinensis var. sinensis, and their structures were determined to be theasapogenol B [beta-D-galactopyranosyl(1-->2)][beta-D-xylopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1-->3)]-beta-D-gulcopyranosiduronic acid with two acyl groups by spectroscopic analysis.
In a black tea (Dimbula) infusion, the potent "sweet and/or juicy" odorants were identified as the cis- and trans-4,5-epoxy-(E)-2-decenals by comparison of their gas chromatography retention indices, mass spectra, and odor quality to those of the actual synthetic compounds. Of the two odorants, cis-4,5-epoxy-(E)-2-decenal has been identified for the first time in the black tea. On the basis of the aroma extract dilution analysis on the flavor distillate obtained using the solvent-assisted flavor evaporation technique from the black tea infusion, these isomers showed higher flavor dilution (FD) factors. The FD factors and concentrations of these odorants in the black tea infusion were observed to be much higher than those from Japanese green tea. In addition, the model studies showed that these odorants were generated from linoleic acid and its hydroperoxides by heating, but the generated amounts of these odorants from linoleic acid were much less than those of its hydroperoxides. It can be assumed from these results that the withering and fermentation, which are characteristic processes during the manufacturing of the black tea, which includes the enzymatic reaction such as lipoxygenase, is one of the most important factors for the formation of the epoxydecenal isomers.
The present study was conducted to investigate the ability of black tea theaflavins to inhibit the off-odor formation from citral under acidic aqueous conditions. Acidic buffer solutions (pH 3.0) containing citral (10 mg/L) and an inhibitor (0-5 mg/L) were stored at 40 degrees C for 2 weeks. The formation of possible off-odorants p-cresol and p-methylacetophenone in the citral solutions was monitored by high-performance liquid chromatography. A mixture of the theaflavins showed inhibitory effects on the formation of both p-cresol and p-methylacetophenone with 50% inhibitory concentrations (IC(50)) of 0.18 and 0.10 mg/L, respectively. Individual theaflavins and a structurally related compound, purpurogallin, also inhibited the formation of both off-odorants, with the lowest IC(50) values for theaflavin 3,3'-digallate (0.17 and 0.06 mg/L for p-cresol and p-methylacetophenone, respectively). On the other hand, a mixture of green tea catechins and its major constituent, (-)-epigallocatechin gallate, showed relatively high IC(50) values for the formation of p-methylacetophenone (1.29 and 1.28 mg/L, respectively) and showed no inhibitory effect on the formation of p-cresol. The results of the sensory evaluation showed that the off-odor intensity of the stored citral solution was significantly decreased by the addition of the theaflavin mixture at concentrations of 0.5 mg/L and above. In addition, the calculation of the odor activity values (OAVs) for the volatile compounds detected by a gas chromatographic analysis indicated that the total OAVs of the major volatile compounds in the citral solution were significantly decreased by the addition of the theaflavins.
Aimed at defining the key drivers for the quality-determining umami taste of a high-grade powdered green tea, called mat-cha, a bioactivity-guided fractionation using solvent extraction, solvent precipitation, preparative chromatographic separations, and human psychophysical experiments was applied on freshly prepared mat-cha. Liquid chromatography-tandem mass spectrometry and one-/two-dimensional nuclear magnetic resonance studies on isolated fractions led to the identification of l-theanine, succinic acid, 3,4,5-trihydroxybenzoic acid (gallic acid), and (1R,2R,3R,5S)-5-carboxy-2,3,5-trihydroxycyclohexyl-3,4,5-trihydroxybenzoate (theogallin) as umami-enhancing compounds in the green tea beverage, and it can be shown by sensory studies that these compounds are able to raise the umami intensity of sodium l-glutamate proportionally.
Deformity of the left breast and axilla observed in Rembrandt's famous painting "Bathsheba at her toilet" (1654, Louvre Paris) has been discussed by several researchers. Proposed diagnoses were breast cancer and abscess due to tuberculosis. The present article reviews previous articles written concerning the left breast abnormalities of Bathsheba and carefully examines other works of Rembrandt modeled by Hendrickje and painted around 1654. Previous diagnosis of breast cancer and tuberculous mastitis is less probable. Because Hendrickje survived for more then 9 years after the painting and in other works modeled by Hendrickje shows no signs of cachexia or permanent changes in the left breast. The most likely diagnosis of the left breast deformity of Bathsheba is a sequela of lactation mastitis abscess following miscarriage or premature childbirth without breast feeding.
BACKGROUND: An oral combined fluoropyrimidine anticancer drug, tegafur/gimeracil/oteracil potassium (S-1), has recently been used alone or in combination for colon cancer. CASE PRESENTATION: The patient was a 42-year-old man with sigmoid colon cancer with direct invasion of the urinary bladder and multiple costal metastases. A diagnosis of T4, M1, stage IV sigmoid colon cancer was made, and curative resection was considered impossible. S-1 at 50 mg/m2 was administered by oral route from day 1 to day 14. Irinotecan (CPT-11) at 40 mg/m2 was administered by intravenous day 1 and 15. This treatment was followed by 2 weeks absent period, and repeated every 4 weeks. Six cycles of administration were performed in total. Following this treatment, the multiple costal metastases resolved. Down-staging to T3, M0, stage IIA was achieved, and curative resection was judged to be possible. CONCLUSION: Occasional cases in which S-1/CPT-11 therapy was effective have been recently reported. The patient's tumor became resectable despite the discovery of colon cancer associated with bone metastasis at the initial examination, offering hope for cancer patients.
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The modification of flat semiconductor surfaces with nanoscale materials has been the subject of considerable interest. This paper provides detailed structural examinations of gold nanoparticles covalently immobilized onto hydrogen-terminated silicon surfaces by a convenient thermal hydrosilylation to form Si-C bonds. Gold nanoparticles stabilized by omega-alkene-1-thiols with different alkyl chain lengths (C3, C6, and C11), with average diameters of 2-3 nm and a narrow size distribution were used. The thermal hydrosilylation reactions of these nanoparticles with hydrogen-terminated Si(111) surfaces were carried out in toluene at various conditions under N2. The obtained modified surfaces were observed by high-resolution scanning electron microscopy (HR-SEM). The obtained images indicate considerable changes in morphology with reaction time, reaction temperature, as well as the length of the stabilizing omega-alkene-1-thiol molecules. These surfaces are stable and can be stored under ambient conditions for several weeks without measurable decomposition. It was also found that the aggregation of immobilized particles on a silicon surface occurred at high temperature (> 100 degrees C). Precise XPS measurements of modified surfaces were carried out by using a Au-S ligand-exchange technique. The spectrum clearly showed the existence of Si-C bonds. Cross-sectional HR-TEM images also directly indicate that the particles were covalently attached to the silicon surface through Si-C bonds.
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New mixed metal clusters with M19 metal frameworks have been synthesized by NaBH4 reduction of Au(NO3)(PMe2Ph) together with AgNO3 in ethanol. Single crystal X-ray diffraction has revealed Au12Ag7 and Au17Ag2 metal skeletons for these clusters, which are best described in terms of bicapped pentagonal antiprismatic cages with a staggered-staggered M(5) ring configuration. These clusters connect the missing link between M13 icosahedral and M25 biicosahedral clusters providing a view of the cluster growth process. A TEM image of this cluster has been observed, which has clearly demonstrated single-sized nano-particles of less than 1.0 nm.
4-Mercapto-4-methyl-2-pentanone is one of the most strongly contributing odorants in the volatile fraction of a Japanese green tea (sen-cha) infusion, and on the basis of the results of an aroma extract dilution analysis, the contribution of this compound to the flavor of the sen-cha infusion varied according to the degree of heating of the tea leaves during the roasting process. The concentration of this odorant in the sen-cha infusion, as with other roasty odorants, increased with the increasing roasting temperature. However, the slope of the increase curve differed with the odor compound, and even if roasting was done at a low temperature, at which the other roasty odorants hardly increased, 4-mercapto-4-methyl-2-pentanone still increased and reached a maximum at 112 degrees C. On the other hand, the amount of 4-mercapto-4-methyl-2-pentanone in sen-cha was a maximum in the first crop, then decreasing in the order of the second and third crops. These results suggested that the amount of 4-mercapto-4-methyl-2-pentanone was closely involved with the quality of sen-cha and that the concentration was dependent on the roasting conditions for the green tea leaves, which might be accompanied by an enzymatic reaction.
BACKGROUND: The aim of the present work was to assess osteopontin (OPN) expression in the colon tissues of ulcerative colitis (UC), Crohn's disease (CD), and diverticulitis (Div) patients. METHODS: This study included three groups: the UC group, CD group, and Div group. Immunohistochemical staining was performed, using an immunoperoxidase method. RESULTS: Regarding OPN expression in intestinal epithelial cells, no difference was noted among the three groups. However, in the submucosa of the UC group, the ratio of two types of large cells (oval and spindle-shaped) expressing OPN was 61.2 +/- 14.4% (mean +/- SD), which was significantly higher than that in the CD group (14.9 +/- 7.0%; P < 0.05) and that in the Div group (11.2 +/- 6.1%; P < 0.05). In addition, in the UC group, the ratio of these cells in the subserosa (50.1 +/- 15.0%; mean +/- SD) was significantly higher than that in the CD group (16.9 +/- 6.2%; P < 0.05) and that in the Div group (12.6 +/- 5.7%; P < 0.05). In a serial section study, the oval-shaped cells were stained for anti-CD 68, while the spindle-shaped cells were stained for anti-vimentin. CONCLUSIONS: OPN in two types of large colon-infiltrating cells is possibly related to one of the pathogenic factors of UC.
Previously, an artificial siderophore complex, the iron(III) complex with tris[2-[(N-acetyl-N-hydroxy)glycylamino]ethyl]amine (TAGE), was constructed in order to understand the effect of intramolecular hydrogen bonding interaction on the siderophore function, and its structural characterization in the solid state was reported (Inorg. Chem. 2001, 40, 190). In this paper, the solution behavior of the M(III)-TAGE (M = Fe, Ga) system has been investigated using (1)H NMR, UV-vis, and FAB mass spectroscopies in efforts to characterize the biological implication of hydrogen bonding networks between the amide hydrogens and coordinating aminohydroxy oxygens of the complex. The temperature dependence of (1)H NMR spectra for Ga(III) complex of TAGE indicates that hydrogen bonding networks are maintained in polar solvents such as DMSO-d(6) and D(2)O. The UV-vis spectra of the Fe(III)-TAGE system under various pH conditions have shown that TAGE forms a tris(hydroxamato)iron(III) complex in an aqueous solution in the pH range 4-8. By contrast, tris[2-[(N-acetyl-N-hydroxy)propylamido]ethyl]amine (TAPE; TAGE analogue that is difficult to form intramolecular hydrogen bonding networks), which has been synthesized as a comparison of TAGE, forms both of bis- and tris(hydroxamato)iron(III) complexes in the same pH range. Both the stability constants (log beta(FeTAGE) = 28.6; beta(FeTAGE) = [Fe(III)TAGE]/([Fe(3+)][TAGE(3)(-)])) and pM (-log[Fe(3+)]) value for Fe(III)TAGE (pM 25) are comparable to those of a natural siderophore ferrichrome (log beta = 29.1 and pM 25.2). The kinetic study of the TAGE-Fe(III) system has given the following rate constants: the rate of the ligand exchange reaction between Fe(III)TAGE and EDTA is 6.7 x 10(-4) s(-1), and the removal rates of iron from diferric bovine plasma transferrin by TAGE are 2.8 x 10(-2) and 6.0 x 10(-3) min(-1). These values are also comparable to those of a natural siderophore desferrioxamine B under the same conditions. In a biological activity experiment, TAGE has promoted the growth of the siderophore-auxotroph Gram-positive bacterium Microbacterium flavescens, suggesting that TAGE mimics the activity of ferrichrome. These results indicate that the artificial siderophore with intramolecular hydrogen bonding networks, TAGE, is a good structural and functional model for a natural ferrichrome.
BACKGROUND: Prognostic indicators for patients with liver cirrhosis accompanied by esophageal varices are hemorrhage of the varices and development of hepatocellular carcinoma (HCC). Although predictors for HCC have been reported, few studies have investigated the correlation between carcinoma development and endoscopic findings of bleeding varices. We examined whether endoscopic variceal findings such as form (F factor), color (C factor) and red color sign (RC factor) predict development of HCC. METHODS: This study included 124 patients with liver cirrhosis who received treatment for bleeding esophageal varices. Patients were followed up with blood chemistries including alpha-fetoprotein and by abdominal ultrasonography and computed tomography. The primary outcome measure of this study was the cumulative incidence of HCC after the treatment for esophageal varices. The secondary measure was whether endoscopic factors predicted the HCC development, and if so, which factors. RESULTS: During follow-up, 32 of the 124 patients developed HCC. The cumulative carcinogenic rate after 3, 5 and 10 years was 11.8, 25.8 and 37.8%, respectively. Among the 32 patients who developed HCC, 29 (90.6%) had large esophageal varices (large F factor) prior to treatment of the varices. As the F factor increased, the percentage of patients who developed HCC also increased. In particular, independent predictors for HCC were: history of blood transfusion (p=0.037), presence of hepatitis C virus antibody (p=0.005), platelet count <7.5 x 10(4)/ml (p=0.004), alpha-fetoprotein level >10 ng/ml (p=0.030), and large F factor (F3) (p=0.002). Variceal RC and C factors were not independent predictors for carcinogenesis. CONCLUSION: The endoscopic F factor rating of bleeding esophageal varices can be a significant predictive factor for HCC in patients with liver cirrhosis.
Ruthenium(II/III) complexes with tripodal tris(pyridylmethyl)amine ligands bearing one, two, or three pivalamide groups (MPPA, BPPA, TPPA: amide-series ligands) or neopentylamine ones (MNPA, BNPA, TNPA: amine-series ligands) at the 6-position of the pyridine ring have been synthesized and structurally characterized. The X-ray structure analyses of the single crystals of these complexes reveal that they complete an octahedral geometry with the tripodal ligand and some monodentate ligands. The amide-series ligands prefer to form a Ru(II) complex, while the amine-series ones give a Ru(III) complex. In the presence of PhIO oxidant, the catalytic activities for epoxidation of olefins, hydroxylation of alkane, and dehydrogenation of alcohol have been investigated using the six ruthenium complexes [Ru(II)(tppa)Cl(2)] (1), [Ru(III)(tnpa)Cl(2)]PF(6) (2), [Ru(II)(bppa)Cl]PF(6) (3), [Ru(III)(bnpa)Cl(2)]PF(6) (4), [Ru(II)(mppa)Cl]PF(6) (5), and [Ru(III)(mnpa)Cl(2)]PF(6) (6). Among them, the amide-series complexes, 1, 3, and 5, showed a higher epoxidation activity in comparison with the amine-series ones, 2, 4, and 6. On the other hand, the latter showed a higher reactivity for hydroxylation, allylic oxidation, and C=C bond cleavage reactions compared with the former. Such a complementary reactivity is interpreted by the character of the ruthenium-oxo species involving electronically equivalent formulas, Ru(V)=O and Ru(IV)-O.
A new-class of promoter electrode bearing a molecular recognition ability has been constructed; the chirality and/or orientation of promoter on the Au electrode surface have affected the electron transfer rate of cytochrome c.
The aim of this study was to clarify the formation mechanism of a potent off-odorant, p-methylacetophenone, from citral under acidic aqueous conditions. An acidic aqueous solution (pH 3.0) containing 10 mg/L of citral was stored at 40 degrees C for 2 weeks. Among the compounds detected in the stored citral solution, 4-(2-hydroxy-2-propyl)benzaldehyde was identified for the first time as a degradation product from citral. The formation of p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde behaved the same when antioxidants were added to the citral solution. In addition, both compounds were formed by the Fe(2+)-induced decomposition of 8-hydroperoxy-p-cymene, another compound identified in the stored citral solution. These results suggested that both p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde can be formed via the same radical intermediate [p-CH3C6H4C(CH3)2O*] that can be derived from the O-O bond homolysis of 8-hydroperoxy-p-cymene. On the other hand, the degradation of 8-hydroperoxy-p-cymene without Fe2+ under acidic aqueous conditions did not yield p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde, but the degradation of citral without Fe2+ did. Therefore, other than the decomposition of 8-hydroperoxy-p-cymene, a mechanism to generate the tert-alkoxy radical intermediate was proposed for the formation of p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde in the citral solution.