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Biomedical subjects

Hideki Masuda

Publications and source records attributed to Hideki Masuda.

At least 55 records · Page 3Linked to original sources
PubMed2002

Structural and spectroscopic features of a cis (hydroxo)-Fe(III)-(carboxylato) configuration as an active site model for lipoxygenases.

In our preliminary communication (Ogo, S.; Wada, S.; Watanabe, Y.; Iwase, M.; Wada, A.; Harata, M.; Jitsukawa, K.; Masuda, H.; Einaga, H. Angew. Chem., Int. Ed. 1998, 37, 2102-2104), we reported the first example of X-ray analysis of a mononuclear six-coordinate (hydroxo)iron(III) non-heme complex, [Fe(III)(tnpa)(OH)(RCO(2))]ClO(4) [tnpa = tris(6-neopentylamino-2-pyridylmethyl)amine; for 1, R = C(6)H(5)], which has a characteristic cis (hydroxo)-Fe(III)-(carboxylato) configuration that models the cis (hydroxo)-Fe(III)-(carboxylato) moiety of the proposed (hydroxo)iron(III) species of lipoxygenases. In this full account, we report structural and spectroscopic characterization of the cis (hydroxo)-Fe(III)-(carboxylato) configuration by extending the model complexes from 1 to [Fe(III)(tnpa)(OH)(RCO(2))]ClO(4) (2, R = CH(3); 3, R = H) whose cis (hydroxo)-Fe(III)-(carboxylato) moieties are isotopically labeled by (18)OH(-), (16)OD(-), (18)OD(-), (12)CH(3)(12)C(18)O(2)(-), (12)CH(3)(13)C(16)O(2)(-), (13)CH(3)(12)C(16)O(2)(-), (13)CH(3)(13)C(16)O(2)(-), and H(13)C(16)O(2)(-). Complexes 1-3 are characterized by X-ray analysis, IR, EPR, and UV-vis spectroscopy, and electrospray ionization mass spectrometry (ESI-MS).

Acetates↗
PubMed2002

Fourier transform IR study of aggregational behavior of N-acetyl-L- and N-butyloxycarbonyl-L-glutamic acid oligomeric benzyl esters in dioxane and benzene: beta-turn --> antiparallel beta-sheet transition.

Oligomeric N-acetyl-L-glutamic acid benzyl esters (AN(p)Z) with exact residue numbers (N(p) = 2, 3, 4, and 5) and N-butyloxycarbonyl-L-glutamic acid benzyl esters (BOCN(p)Z) with exact residue numbers (N(p) = 4, 5, 6, and 8) are synthesized by a stepwise procedure in a liquid phase. The aggregational behavior of these oligomeric molecules in dioxane and benzene is examined by Fourier transform IR spectra. In particular, the concentration dependence of the IR spectra for the AN(p)Z solutions with N(p) values of 4 (A4Z) and 5 (A5Z) shows that the predominant antiparallel beta-sheet structure is stabilized above the critical aggregation concentration (cac), while other conformations including beta-turns may coexist below the cac. This fact provides evidence that aggregation induces the conformational transition from other conformers (probably beta-turns) to an antiparallel beta-sheet form. The IR results for the A3Z and A2Z solutions indicate that specific conformers (beta-turns), which are different from the beta-sheet structure, may be preferentially stabilized upon aggregation. Thus, the critical residue number of the AN(p)Z oligopeptides, which is essential for formation of a rodlike aggregate in dioxane and benzene, is 4 or 5.

Amino Acid Sequence↗
PubMed2002

Identification of potent odorants in different green tea varieties using flavor dilution technique.

Two kinds of pan-fired green teas (Japanese Kamairi-cha and Chinese Longing tea) were compared with the common Japanese green tea (Sen-cha). Application of the aroma extract dilution analysis (AEDA) using the volatile fraction of the Sen-cha, Kamairi-cha and Longing tea infusions revealed 32, 51, and 52 odor-active peaks with flavor dilution factors between 16 and 1024, respectively. (Z)-1,5-Octadien-3-one (metallic, geranium-like), 4-mercapto-4-methyl-2-pentanone (meaty, black currant-like), methional (potato-like), (E,Z)-2,6-nonadienal (cucumber-like), and 3-methylnonane-2,4-dione (green, fruity, hay-like) showed high flavor dilution factors in all varieties. In addition, 2-acetyl-1-pyrroline (popcorn-like), 2-ethyl-3,5-dimethylpyrazine (nutty), 2,3-diethyl-5-methylpyrazine (nutty), and 2-acetyl-2-thiazoline (popcorn-like) belonged to the most potent odorants only in the pan-fired green teas. Among these odorants, 2-acetyl-1-pyrroline and 2-acetyl-2-thiazoline were identified for the first time among the tea volatiles.

Chromatography, Gas↗
PubMed2002

Spectroscopic and structural characterization of copper(II) and palladium(II) complexes of a lichen substance usnic acid and its derivatives. Possible forms of environmental metals retained in lichens.

The metal binding properties of a phenolic lichen substance usnic acid (UA) and its acetyl and enamine derivatives 9-O-acetylusnic acid (MAUA), 7,9-di-O-acetylusnic acid (DAUA), Delta(2,11)-enaminousnic acid (EUA), and N-substituted Delta(2,11)-enaminousnic acids have been studied by synthetic and spectroscopic methods, and the structures of copper(II) and palladium(II) complexes have been established by the X-ray diffraction method. Cu(II) reacted with UA and DAUA to give the binary complexes Cu(UA)(2) x H(2)O and Cu(DAUA)(2), respectively, and Cu(bpy) (bpy=2,2'-bipyridine) formed ternary complexes with UA and DAUA. Pd(II) also reacted with UA, DAUA, EUA, and N-substituted Delta(2,11)-enaminousnic acids to give the corresponding binary complexes. All the isolated complexes are insoluble in water and soluble in most organic solvents. They exhibited very strong absorption and circular dichroism spectral peaks in the UV region. The (1)H-NMR spectrum in CDCl(3) of the Pd(II) complex of N-phenyl-Delta(2,11)-enaminousnic acid (PEUA), Pd(PEUA)(2) x C(6)H(6), showed that the C(4)-proton signal suffered a large upfield shift (0.86 ppm) due to the ring current effect of the N-phenyl moiety. X-Ray crystal structure analysis has been performed for Cu(bpy)(UA)(ClO(4)) x CH(3)OH, Pd(MEUA)(2) x C(6)H(6), and Pd(PEUA)(2) x C(6)H(6). Cu(bpy)(UA)(ClO(4)) x CH(3)OH has a square-pyramidal structure with the two nitrogen atoms of bpy and the two oxygen atoms of the mono-deprotonated B ring of UA in the equatorial positions, while Pd(II) binds with two molecules of MEUA or PEUA in the trans configuration through the nitrogen and oxygen atoms with deprotonation. The N-phenyl ring of PEUA in Pd(PEUA)(2).C(6)H(6) was revealed to be located close to the C(4) proton as indicated by (1)H-NMR. Isolation of Cu(2)(bpy)(2)(UA)(NO(3))(2) x 2H(2)O suggests that UA has two metal binding sites that can form polymeric complexes. The present results substantiate the metal binding ability and the structures of the complexes of usnic acid and other substances from lichens as biomonitors of environmental metal ions.

Anti-Infective Agents↗
PubMed2002

Reactivity of hydroperoxide bound to a mononuclear non-heme iron site.

The first isolation and spectroscopic characterization of the mononuclear hydroperoxo-iron(III) complex [Fe(H(2)bppa)(OOH)](2+) (2) and the stoichiometric oxidation of substrates by the mononuclear iron-oxo intermediate generated by its decomposition have been described. The purple species 2 obtained from reaction of [Fe(H(2)bppa)(HCOO)](ClO(4))(2) with H(2)O(2) in acetone at -50 degrees C gave characteristic UV-vis (lambda(max) = 568 nm, epsilon = 1200 M(-1) cm(-1)), ESR (g = 7.54, 5.78, and 4.25, S = (5)/(2)), and ESI mass spectra (m/z 288.5 corresponding to the ion, [Fe(bppa)(OOH)](2+)), which revealed that 2 is a high-spin mononuclear iron(III) complex with a hydroperoxide in an end-on fashion. The resonance Raman spectrum of 2 in d(6)-acetone revealed two intense bands at 621 and 830 cm(-1), which shifted to 599 and 813 cm(-1), respectively, when reacted with (18)O-labeled H(2)O(2). Reactions of the isolated (bppa)Fe(III)-OOH (2) with various substrates (single turnover oxidations) exhibited that the iron-oxo intermediate generated by decomposition of 2 is a nucleophilic species formulated as [(H(2)bppa)Fe(III)-O*].

Alkanes↗
PubMed2002

E-cadherin expression is inversely proportional to tumor size in experimental liver metastases.

OBJECTIVE: The role of E-cadherin in the metastatic process remains controversial. In this study, we examined what role E-cadherin plays in relation to tumor size and microvessel density (MVD) of the liver metastatic lesion. MATERIALS AND METHODS: In F344 male rats, metastatic lesions were made by injecting RCN-9 cells into the spleen. We performed an immunohistochemical evaluation of E-cadherin and MVD in the metastatic lesions. According to a previous report, we focused on tumor sizes ranging from 2 to 3 mm, and the metastatic nodules were divided into two groups considering the value of the MVD. RESULTS: The expression of E-cadherin was inversely proportional to tumor size (r = -0.882, P < 0.0001). MVD was directly proportional to metastatic tumor size (r = 0.726, P = 0.001). MVD in group A, in which the tumor size was 2.3 mm or more, was significantly higher than that in group B, in which the tumor size was less than 2.3 mm (3.13 +/- 1.65% vs 1.75 +/- 0.27%; P = 0.0069). The expression ratio of E-cadherin in group A was 28.21 +/- 16.36%, while it was 82.33 +/- 16.35% in group B (P = 0.0003). CONCLUSION: In liver metastasis, E-cadherin's function is preserved when the tumor is small and E-cadherin's expression is reduced in large tumors in which neovascularization is increased.

Animals↗
PubMed2002

Ulcerative colitis associated with Takayasu's disease in two patients who received proctocolectomy.

Ulcerative colitis (UC) associated with Takayasu's disease (TD) is not common in Japan. Here, we report two patients with both diseases who received a total proctocolectomy. Patient 1, a 41-year-old woman with chronic continuous type UC, was first diagnosed with TD at the age of 10 years. Subsequently, she was diagnosed with UC and rectal cancer. HLA typing showed A2, A31(19), B52(5), and DR2(DRB1*1502). Coronary angiography showed 90% narrowing of the right coronary artery (RCA). After alleviating the RCA narrowing by percutaneous transluminal coronary angioplasty (PTCA), we performed a total proctocolectomy and ileostomy. Patient 2, a 20-year-old woman, was first diagnosed with TD at the age of 13 years. Severe symptoms, indicating fulminant UC, started 1 month prior to hospitalization. She was judged as needing surgery because the symptoms were not alleviated even with high doses of prednisolone. HLA typing showed A2, A31(19), B52, B61(40), DR2(DRB1*1502), and DR4 (DRB1*0405). Aortography showed a narrowing of the right renal artery; however, her renal function was normal. Based on these findings, we performed a three-stage operation for total proctocolectomy. Previously, we have reported that the DRB1*1502 and DRw11 genes were closely related to the intractability of UC. To date, we have not determined whether or how the DRB1*1502 gene might be related to TD. As the number of cases of UC associated with TD increases, it will be necessary to examine their DR2 subtypes.

Adult↗
PubMed2002

(Catecholato)iron(III) complexes: structural and functional models for the catechol-bound iron(III) form of catechol dioxygenases.

Catechol dioxygenases are mononuclear non-heme iron enzymes that catalyze the oxygenation of catechols to aliphatic acids via the cleavage of aromatic rings. In the last 20 years, a number of (catecholato)iron(III) complexes have been synthesized and characterized as structural and functional models for the catechol-bound iron(III) form of catechol dioxygenases. This review focuses on the structural and spectroscopic characteristics and oxygenation activity of the title complexes.

Catechol 1,2-Dioxygenase↗
PubMed2002

Effects of replacement of prolines with alanines on the catalytic activity and thermostability of inorganic pyrophosphatase from thermophilic bacterium PS-3.

Each of the 10 proline residues of the inorganic pyrophosphatase (PPase) subunit of thermophilic bacterium PS-3 (PS-3) was replaced with alanine by the PCR-mutagenesis method. The variants were classified into three groups according to the effects of the replacements on their catalytic activities in 20 mM Tris-HCl, pH 7.8, containing 5 mM MgCl(2): the catalytic activity was (i) slightly affected (P39A and P69A), (ii) considerably reduced (P14A, P43A, P59A, and P116A), and (iii) completely or almost completely abolished (P72A, P100A, P104A, and P146A). HPLC-gel chromatography in the presence of 5 mM MgCl(2) revealed the following subunit assembly of the variants: group (i), a hexamer; group (ii), a hexamer or a mixture of a hexamer and a trimer, although the hexamer was predominant; and group (iii), a trimer or a monomer. The thermostability of the variant PPases depended upon the amount of hexamer remaining in the presence of Mg(2+) at high temperature. The results indicated that the hexamer state formed through protomer-protomer and trimer-trimer interactions is necessary for the PS-3 PPase to retain the correct structure for full catalytic activity and thermostability.

Alanine↗
PubMed2002

Antiallergic effect of flavonoid glycosides obtained from Mentha piperita L.

Six flavonoid glycosides, eriocitrin (1), narirutin (2), hesperidin (3), luteolin-7-O-rutinoside (4), isorhoifolin (5), diosmin (6), rosmarinic acid (7) and 5,7-dihydroxycromone-7-O-rutinoside (8), were isolated from the aerial part of Mentha piperita L. Among these compounds, compound 4 showed a potent inhibitory effect on histamine release induced by compound 48/80 and antigen-antibody reaction. This compound was more effective than luteolin and luteolin-7-O-glucoside in inhibiting histamine release from rat peritoneal mast cells. Compound 4 also caused a dose-related inhibition of the antigen-induced nasal response and significant effects were observed at doses of 100 and 300 mg/kg. These results indicate that compound 4 may be clinically useful in alleviating the nasal symptoms of allergic rhinitis.

Animals↗
PubMed1997

Weak Interactions in Ternary Copper(II) Complexes with Iodotyrosinates. Biological Significance of the Iodines in Thyroid Hormones.

Structures and spectroscopic studies have been carried out on ternary copper(II) complexes, Cu(DA)(AA), with aromatic amino acids (AA = 3,5-diiodo-L-tyrosinate (L-I(2)tyr), 3-iodo-L-tyrosinate (L-Ityr), L-tyrosinate) and diamines (DA = 1,10-phenanthroline, 2,2'-bipyridine (bpy), 2-(aminomethyl)pyridine, histamine (hista), or ethylenediamine). The charge transfer (CT) absorption bands observed in the near UV region and the CD spectral magnitude anomaly observed in the d-d region indicated an effective aromatic ring stacking interaction between the side-chain phenol ring of AA and the aromatic diamine DA in the complexes in solution. Two complexes, [Cu(bpy)(L-Ityr)(H(2)O)].NO(3).CH(3)OH.H(2)O (1) and [Cu(hista)(L-I(2)tyrO(-))(H(2)O)](2).2H(2)O (2), where O(-) represents the deprotonated form of the phenol hydroxyl group, were isolated as single crystals, and their structures were determined by X-ray analysis. Both 1 and 2 crystallized in the monoclinic space group P2(1), with a = 7.549(1) Å, b = 11.431(1) Å, c = 14.292(2) Å, beta = 100.08(1) degrees, and Z = 2 for 1 and a = 9.9642(9) Å, b = 15.825(1) Å, c = 12.451(1) Å, beta = 91.565(7) degrees, and Z = 2 for 2. The molecular structures of 1 and 2 revealed the intramolecular aromatic ring stacking between DA and the iodinated phenol ring of Ityr and I(2)tyrO(-), respectively, in correspondence with the solution spectral observations. The stacking with hista was found to be weaker than that with bpy from the interplanar distances in 1 and 2 and the CT band intensities in solution. The molecular and crystal structures revealed some intermolecular iodine-aromatic ring and iodine-oxygen interactions as well as some hydrogen bonds involving the phenol hydroxyl group.

Journal Article↗
PubMed1996

Structures and Stabilities of Ternary Copper(II) Complexes with 3,5-Diiodo-L-tyrosinate. Weak Interactions Involving Iodo Groups.

Structures and stabilities of the ternary copper(II) complexes Cu(DA)(AA), where AA refers to 3,5-diiodo-L-tyrosinate (I(2)tyr) or L-tyrosinate (Tyr) and DA refers to 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), 2-(aminomethyl)pyridine (ampy), histamine (hista), or ethylenediamine (en), have been investigated by potentiometric, spectroscopic, and X-ray diffraction methods. The stability constants have been determined by potentiometric titrations at 25 degrees C and ionic strength I = 0.1 M (KNO(3)). The equilibrium constants K for a hypothetical equilibrium, Cu(DA)(Ala) + Cu(en)(AA) Cu(DA)(AA) + Cu(en)(Ala) where Ala refers to L-alanine, have been calculated from the determined overall stability constants of the ternary complexes for estimating the stability enhancement due to the stacking interaction between the aromatic rings in Cu(DA)(AA). Large positive log K values have been obtained for the Cu(DA)(I(2)tyrOH) and Cu(DA)(I(2)tyrO(-)) systems (DA = phen or bpy, OH and O(-) refer to the protonated and deprotonated forms of the phenol moiety, respectively), indicating that the complexes are stabilized by effective stacking. Differences between the log K values for Cu(DA)(I(2)tyr) and Cu(DA)(Tyr) systems indicate that the iodine substituents greatly contribute to the stability enhancement. A distinct circular dichroism (CD) magnitude anomaly was also observed for the systems with large log K value, supporting the existence of the stacking interaction in Cu(DA)(AA). Two complexes, [Cu(bpy)(I(2)tyrO(-))(H(2)O)].2H(2)O (1) and [Cu(bpy)(I(2)tyrOH)(NO(3))].CH(3)OH (2), have been isolated as crystals and analyzed by the X-ray diffraction method. Both 1 and 2 crystallized in the orthorhombic space group P2(1)2(1)2(1) with four molecules in a unit cell of dimensions a = 9.2339(4), b = 16.9230(8), and c = 14.8584(5) Å for complex 1, and a = 11.2240(8), b = 11.715(1), and c = 17.966(2) Å for complex 2. The central Cu(II) ion for both complexes has a similar distorted five-coordinate square-pyramidal geometry with the equatorial positions occupied by the two nitrogen atoms of bpy and the nitrogen and oxygen atoms of I(2)tyr, and the apical position is occupied by a water molecule (for 1) or a nitrate ion (for 2). The opposite site to the axial water or nitrate oxygen atom is intramolecularly occupied by the side chain aromatic ring, which is approximately parallel to the copper coordination plane with the average spacing of 3.31 or 3.30 Å for complex 1 or 2, respectively, directly exhibiting the effective stacking interaction between the aromatic rings in the solid state. Distances between the iodine and one of the pyridine rings of bpy (3.79 Å for 1 and 3.56 Å for 2) are shorter than the van der Waals distance (3.85 Å), implying that the iodine substituent may be involved in a weak bonding interaction with the pyridine ring. Effects of the iodine substituents on the stacking interactions between the diiodophenol side ring and the coordinated aromatic diamine and their possible biological relevance have been discussed.

Journal Article↗
PubMed1996

Intermolecular Ferromagnetic and Antiferromagnetic Interactions in Halogen-Bridged Copper(I) Imino Nitroxides: Crystal Structures and Magnetic Properties of [Cu(I)(&mgr;-X)(imino nitroxide)](2) (X = I or Br).

Reaction of CuI or CuBr with some imino nitroxides in methanol gave the halogen bridged dinuclear Cu(I) complexes [Cu(&mgr;-I)(impy)](2) (1), [Cu(&mgr;-I)(immepy)](2) (2), [Cu(&mgr;-Br)(immepy)](2) (3), and [Cu(&mgr;-Br)(imph-NO(2))](2) (4), respectively (impy = 2-(2'-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl, immepy = 2-(6'-methyl-2'-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl, imph-NO(2) = 2-(4'-nitrophenyl)-4,4,5,5-tetramethyl-4,6-dihydro-1H-imidazolyl-1-oxyl). Crystal structures and magnetic properties have been studied. Complexes 1-4 have dimeric structures where two copper ions are doubly bridged by halide ions in a &mgr;(2) fashion. In 1-3, each copper ion is tetrahedral with a bidentate imino nitroxide and two halide ions, and the two copper ions are separated by 2.592(2), 2.6869(8), and 2.7357(6) Å, respectively. In 4, triangular coordination sites of the copper ions are completed with a nitrogen atom from the imino nitroxide and two bromide ions bridging the two copper ions with a separation of 3.074(2) Å. Ligand imino nitroxides in 1-4 form one-dimensional radical chains, and the chains are linked with halocuprate dimer units. Structural and magnetic susceptibility data support that radicals in 1 and 4 are ferromagnetically stacked, while radicals in 2 and 3 form an antiferromagnetic chain. The magnetic behaviors are discussed in connection with the stacking modes of the radicals and bridging conformations. Crystal data (Mo Kalpha, lambda = 0.71069 Å): 1, orthorhombic, space group P2(1)2(1)2(1), a = 17.807(2) Å, b = 8.595(2) Å, c = 19.336(6) Å, and Z = 4; 2, monoclinic, space group P2(1)/c, a = 9.941(2) Å, b = 18.482(2) Å, c = 8.337(2) Å, beta = 96.41(2) degrees, and Z = 2; 3, monoclinic, space group P2(1)/c, a = 9.964(6) Å, b = 18.167(4) Å, c = 8.009(7) Å, beta = 95.81(6) degrees, and Z = 2; 4, monoclinic, space group P2(1)/c, a = 11.991(7) Å, b = 17.998(8) Å, c = 7.215(6) Å, beta = 104.07(6) degrees, and Z = 2.

Journal Article↗
PubMedDate not supplied

Two subtypes in colorectal mucinous carcinoma in relation to microsatellite instability.

BACKGROUND/AIMS: Although some investigators have attempted to divide colorectal mucinous adenocarcinoma into two entities, there have been few reports describing microsatellite instability of each subtype. In this study, we elucidated the clinicopathological features of subtypes in mucinous carcinoma, especially the relationship between microsatellite instability and each subtype. METHODOLOGY: The present study included 33 patients with mucinous colorectal cancer. The 33 patients were classified into two groups; the papillotubular type group (n = 22) and the mucocellular type group (n = 11). The clinicopathological aspects and microsatellite instability were examined. RESULTS: Significant differences were found between the papillotubular type group and the mucocellular type group regarding the following findings such as lymphatic invasion, lymph node metastasis, peritoneal metastasis, and Dukes stage. The mucocellular type group had 2 cases with high-frequency microsatellite instability, 7 cases with low-frequency microsatellite instability and 2 cases with microsatellite stability. Conversely, the papillotubular type group included 12 cases with high-frequency microsatellite instability, 3 cases with low-frequency microsatellite instability and 7 cases with microsatellite stability. The ratio of cases with high-frequency microsatellite instability in the mucocellular type group (18.1%) was significantly lower than that of the papillotubular type group (54.5%) (P = 0.0463). The 5-year survival rate of the mucocellular type group (29.1%) was significantly lower than that of the papillotubular type group (70.3%) (P = 0.0282). CONCLUSIONS: Colorectal mucinous carcinoma needs to be classified into two groups, papillotubular type and mucocellular type, because of significant differences in microsatellite instability and patients' survival.

Adenocarcinoma, Mucinous↗
PubMedDate not supplied

Anterior approach for resection of metastatic liver tumors infiltrating the caudate lobe.

A 57-year-old woman with a cecal cancer underwent a curative, right hemicolectomy. One year after the operation, she was noted to have liver metastases with two focuses. One was 12 cm in diameter and was located mainly at the medial hepatic segment and infiltrating into the caudate lobe. The inferior vena cava and major hepatic vein were compressed and/or involved with the tumor. The patient underwent an extended left lobectomy using an anterior approach, which gave us sufficient visualization. The patient remains healthy 4 years after the operation. Hepatectomy using an anterior approach may be useful for expanding the surgical indications for metastatic disease.

Cecal Neoplasms↗