Biomedical subjects

Noboru Kitamura

Publications and source records attributed to Noboru Kitamura.

At least 19 recordsLinked to original sources

PubMed2006

Synthesis and spectroscopic properties of platinum(II) terpyridine complexes having an arylborane charge transfer unit.

Synthesis, redox, spectroscopic, and photophysical properties of a new class of Pt(II) complexes of the type [PtLnCl]+ are reported, where Ln is 4'-phenyl(dimesitylboryl)-2,2':6',2"-terpyridine (L1) or 4'-duryl(dimesitylboryl)-2,2':6',2"-terpyridine (L2). The free L1 or L2 ligand in CH3CN shows the absorption band responsible for intramolecular charge transfer (CT) from the pi-orbital of the aryl group in L1 or L2 (pi(aryl)) to the vacant p-orbital on the boron atom (p(B)), in addition to pipi* absorption in the 2,2':6',2"-terpyridine (tpy) unit. In particular, the L1 ligand shows an intense CT absorption band as compared with L2. Such intramolecular pi(aryl)-p(B) CT interactions in L1 give rise to large influences on the redox, spectroscopic, and photophysical properties of [PtL1Cl]+. In practice, [PtL1Cl]+ shows strong room-temperature emission in CHCl3 with the quantum yield and lifetime of 0.011 and 0.6 micros, respectively, which has been explained by synergetic effects of Pt(II)-to-L1 MLCT and pi(aryl)-p(B) CT interactions on the electronic structures of the complex. In the case of [PtL2Cl]+, the dihedral angle between the planes produced by the tpy and duryl(dimesitylborane) groups is very large (84 degrees ) as compared with that between the tpy and phenyl(dimesitylborane) units in [PtL1Cl]+ (26-39 degrees ), which disturbs electron communication between the Pt(II)-tpy and arylborane units in [PtL2Cl]+. Thus, [PtL2Cl]+ is nonemissive at room temperature. The important roles of the synergetic CT interactions in the excited-state properties of the [PtL1Cl]+ complex are shown clearly by emission quenching of the complex by a fluoride ion. The X-ray crystal structure of [PtL1Cl]+ is also reported.

Journal Article↗

PubMed2006

Structural, redox, and photophysical studies of the tetra(pyridyl)porphyrin complex containing four (2,2'-bipyridine)(2,2':6',2"-terpyridine)ruthenium(II) groups.

New hybrid complexes of polypyridyl ruthenium and pyridylporphyrins have been prepared by the coordination of pyridyl nitrogens to the ruthenium centers. A 1:4 hybrid complex, [{Ru(bpy)(trpy)}4(mu4-H2Py4P)]8+ ([1]8+) (bpy = 2,2'-bipyridine; trpy = 2,2':6',2"-terpyridine; H2Py4P = 5,10,15,20-tetra(4-pyridyl)porphyrin), has been characterized by the single-crystal X-ray diffraction method. A 1:1 complex, [{Ru(bpy)(trpy)}(H2PyT3P)]2+ ([2]2+) (H2PyT3P = 5-(4-pyridyl)tritolylporphyrin) has also been prepared. The Soret band of the porphyrin ring shifts to longer wavelength with some broadening, the extent of the shift being larger for [1]8+. Cyclic voltammograms of the two complexes show simple overlap of the component redox waves. The complexes are weakly emissive at room temperature, which becomes stronger at lower temperatures. While [1]8+ at >140 K and [2]2+ at 77-280 K show only porphyrin fluorescence, [1]8+ at <140 K shows ruthenium and porphyrin phosphorescence, in addition to the porphyrin fluorescence.

Journal Article↗

PubMed2006

A thermodynamic study on the complexation between riboflavin and a diaminotriazine derivative mediated by triple hydrogen bonds at water/oil interfaces.

The changes in Gibbs free energy (DeltaG (int)), enthalpy (DeltaH (int)) and entropy (TDeltaS (int)) upon complexation between riboflavin (RF) and N,N-dioctadecyl-[1,3,5]triazine-2,4,6-triamine (DTT), mediated by triple hydrogen bonds at water/carbon tetrachloride, trichloroethylene and chloroform interfaces, were determined via temperature-controlled interfacial tension measurements. It was shown that hydrogen bonding interactions between RF and DTT were best characterized by large and negative DeltaH (int) values, unlike those predicted from either the polarity in each phase or the arithmetic average of the polarities in the two phases. Furthermore, the DeltaH (int) values became more positive as the dielectric constant of the oil phase was increased. These results strongly indicate that DeltaH (int) is governed by the dielectric properties of the oil phase. Adsorption of RF, DTT and the RF-DTT complex at the water/oil interface gave rise to restrictions on the translational and rotational motions of these species, as demonstrated by the DeltaS (int) values observed, which is another characteristic of interfacial complexation. The thermodynamic parameters evaluated in the present study revealed the characteristic complexation behavior that occurs at a water/oil interface, as mediated by hydrogen bonding.

Hydrogen Bonding↗

PubMed2006

Low-dose epoprostenol improved pulmonary hypertension in a patient with systemic lupus erythematosus.

A 43-year-old Japanese woman was referred to our hospital in 1997 because of Raynaud's phenomenon. Systemic lupus erythematosus was diagnosed on the basis of the presence of antinuclear antibody (1:1,280), anti-DNA antibody (1:640), anti-Sm antibody, antiphospholipid antibody, lymphopenia, and proteinuria. She developed pulmonary fibrosis in 1999 and pulmonary hypertension in 2001. In October 2002, a 24-hr continuous infusion of epoprostenol was started. Dyspnea, Raynaud's phenomenon, and pulmonary hypertension improved with low-dose epoprostenol (3.0 to 4.0 ng kg(-1) min(-1)). The patient could not tolerate larger doses of epoprostenol so 4.0 ng kg(-1) min(-1) was selected as the maintenance dose. The clinical course was uneventful at this dosage. It appears that pulmonary hypertension can be controlled with low-dose epoprostenol such as 3.0 to 4.0 ng kg(-1) min(-1) in some rheumatic patients.

Adult↗

PubMed2006

Raman microspectroscopy/imaging study on phase-vanishing processes of fluorous biphase systems in microchannel-microheater chips.

Temperature-dependent phase-vanishing processes between perfluorohexane (FC-72) and n-heptane (C7H16, volume ratio of 1:1 and phase-vanishing temperature>41 degrees C), were studied in a glass microchannel-microheater chip under solution-flow conditions. Without applying a voltage to the heater at 21 degrees C, the two liquids in the microchannel were separated into two streams at a solution flow rate (v) of 0.975 cm/s, while the phase boundary between FC-72 and C7H16 vanished in the downstream side of the heater at V=4.5 V. Then, we conducted Raman intensity imaging during the phase vanishing processes in the microchannel by monitoring the band at 756 (FC-72) or 1456 cm-1 (C7H16). At V=4.5 V and v=0.975 cm/s, although no phase boundary between the two liquids in the microchannel was observed, the relevant Raman intensity images indicated the inhomogeneous nature of the solution, and distribution of C7H16 to the FC-72 phase along with solution flow was observed.

Journal Article↗

PubMed2005

Luminescence ranging from red to blue: a series of copper(I)-halide complexes having rhombic {Cu2(mu-X)2} (X = Br and I) units with N-heteroaromatic ligands.

A series of Cu(I) complexes formulated as [Cu(2)(mu-X)(2)(PPh(3))(L)(n)] were prepared with various mono- and bidentate N-heteroaromatic ligands (X = Br, I; L = 4,4'-bipyridine, pyrazine, pyrimidine, 1,5-naphthyridine, 1,6-naphthyridine, quinazoline, N,N-dimethyl-4-aminopyridine, 3-benzoylpyridine, 4-benzoylpyridine; n = 1, 2). Single-crystal structure analyses revealed that all the complexes have planar {Cu(2)X(2)} units. Whereas those with monodentate N-heteroaromatic ligands afforded discrete dinuclear complexes, bidentate ligands formed infinite chain complexes with the ligands bridging the dimeric units. The long Cu...Cu distances (2.872-3.303 A) observed in these complexes indicated no substantial interaction between the two Cu(I) ions. The complexes showed strong emission at room temperature as well as at 80 K in the solid state. The emission spectra and lifetimes in the microsecond range were measured at room temperature and at 80 K. The emissions of the complexes varied from red to blue by the systematic selection of the N-heteroaromatic ligands (lambda(em)(max): 450 nm (L = N,N-dimethyl-4-aminopyridine) to 707 nm (L = pyrazine)), and were assigned to metal-to-ligand charge-transfer (MLCT) excited states with some mixing of the halide-to-ligand (XL) CT characters. The emission energies were successfully correlated with the reduction potentials of the coordinated N-heteroaromatic ligands, which were estimated by applying a simple modification based on the calculated stabilization energies of the ligands by protonation.

Journal Article↗

PubMed2005

A case of systemic lupus erythematosus complicated by alveolar hemorrhage and cytomegalovirus colitis.

We report a rare case of systemic lupus erythematosus (SLE) complicated by alveolar hemorrhage and cytomegalovirus (CMV) colitis. Despite the successful treatment of lupus nephritis by steroid pulse therapy, the patient developed an acute alveolar hemorrhage 2 months later. Cyclophosphamide pulse therapy ameliorated the hemorrhage. One month later, she suddenly developed melena secondary to CMV colitis. Antiviral therapy was successful. We emphasize the importance of timely and precise differential diagnosis for successful management of complicated SLE.

Adult↗

PubMed2005

Spectroscopic and excited-state properties of Tri-9-anthrylborane III: crystal and spectroscopic polymorphisms.

We found that tri-9-anthrylborane (TAB) recrystallized from benzene produced both red cubic-like (R-form) and orange hexagon-like crystals (O-form). In both crystal forms, six TAB molecules are arranged in a honeycomb structure in the ab plane and benzene molecules are incorporated in the honeycomb structure, whose spatial geometry and the total number of benzene rings in the unit cell are different between the two forms: polymorphs with a different benzene content. In the R-form crystal, furthermore, interlayer stacking between left- and right-handed helical TAB molecules was observed in the ac plane, while each layer composed of stacked TAB molecules along the c axis was separated by benzene molecules in the O-form crystal, giving rise to more dense packing of TAB in the R-form crystal as compared to that in the O-form. Reflecting the crystal structures of the two forms, the charge transfer (CT) absorption and fluorescence spectra of the R-form crystal were shifted to the longer wavelength as compared to those in the O-form (i.e., crystal and spectroscopic polymorphisms) and, therefore, electronic interactions between TAB were stronger in the R-form as compared to those in the O-form. Furthermore, in addition to the main absorption (lambdamaxa= 499 nm) and fluorescence peaks (lambdamaxf = 570 nm), distinct absorption (lambdaa = approximately 470 nm) and fluorescence bands (lambdaf = approximately 600 nm) were observed for the R-form crystal, while the relevant absorption band in the O-form crystal (lambdaa = approximately 460 nm) or in solution (lambda(a) = approximately 435 nm) was ambiguous. The results were discussed in terms of participation of the higher energy second CT transition in TAB.

Journal Article↗

PubMed2005

Laser-induced liquid-to-droplet extraction of chlorophenol: photothermal phase separation of aqueous triethylamine solutions.

Thermal phase separation of aqueous triethylamine (TEA) solutions (TEA wt % = 6.5-6.7 in H2O) was induced by irradiating a focused 1064-nm laser beam (spot size approximately 1 mum) under an optical microscope, and this produced a single micrometer-sized TEA droplet as demonstrated by in situ Raman microspectroscopy. Since H2O absorbs 1064-nm light, heat is generated at the focal spot of the incident laser beam, giving rise to photothermal phase separation of the aqueous TEA solution. The TEA droplet produced by phase separation was trapped simultaneously by the incident laser beam. In the presence of p-chlorophenol (CP) in an aqueous TEA solution, laser-induced photothermal phase separation and simultaneous TEA droplet formation brought about extraction/concentration of CP from the surrounding solution phase to the TEA droplet (approximately 15-mum diameter and 1.7-pL volume). Raman microspectroscopy demonstrated that the distribution coefficient of CP (KD) between the solution phase and the single TEA droplet was KD(drop) = approximately 21, while that in a bulk TEA/H2O system was KD(bulk) = 4.7. The larger KD(drop) value as compared to KD(bulk) was discussed in terms of radiation pressure exerted on CP in the TEA droplet.

Journal Article↗

PubMed2005

Temperature dependent emission of hexarhenium(III) clusters [Re6(mu3-S)8X6]4- (X = Cl-, Br-, and I-): analysis by four excited triplet-state sublevels.

Temperature (T) dependences of the emission spectra and lifetimes of hexarhenium(III) clusters, [Re6(mu3-S)8X6]4- (X = Cl-, Br-, and I-), in the crystalline phase were studied in detail. An increase in T from 30 to 70 K resulted in a red-shift of the emission spectrum of the cluster, while an increase in T above 70 K gave rise to a gradual blue-shift of the spectrum. On the other hand, the emission lifetime of the cluster decreased sharply from 30-40 to 13-20 micros on going from 30 to 60 K, while that decreased gradually above 60 K: 5-6 micros at 290 K. Such emission behaviors of [Re6(mu3-S)8X6]4- were observed irrespective of X. The results were then analyzed by assuming the contributions of the emissions from the lowest-energy excited triplet-state sublevels. The present study demonstrated that the characteristic T dependent emission spectra and lifetimes of [Re6(mu3-S)8X6]4- were explained reasonably by a single context of the contributions of the emissions from four excited triplet-state sublevels.

Journal Article↗

PubMed2005

Spectroscopic and excited-state properties of tri-9-anthrylborane II: Electroabsorption and electrofluorescence spectra.

Electroabsorption and electrofluorescence spectroscopies were conducted for tri-9-anthrylborane (TAB) doped in poly(methyl methacrylate) films (1.0 mol %) to reveal the spectroscopic and excited-state properties of the compound. TAB showed three distinct absorption bands: bands I [(19 - 25) x 10(3) cm(-1)], II [(25-31) x 10(3) cm(-1)], and III (>31 x 10(3) cm(-1)). The electroabsorption spectrum demonstrated that the electronic transitions in bands I and III accompanied electric dipole moment changes (Deltamu), while the change in the molecular polarizability contributed mainly to electroabsorption band II. Because of the similarities of the electroabsorption spectrum of band II with that of anthracene itself, band II was assigned to the electronic transition to the locally excited (LE) state of the anthryl group. On the other hand, bands I and III were best described by the electronic transitions to the excited charge-transfer (CT) states. The study demonstrated furthermore that the Deltamu value of TAB accompanied by the lowest-energy electronic transition was as large as 7.8 D, which agreed very well with that determined by the solvent dependences of the absorption and fluorescence maximum energies of TAB (approximately 8.0 D, ref 1): Deltamu = 7.8-8.0 D. The results proved explicitly that the excited state of TAB was localized primarily on the p orbital of the boron atom. Despite the dipole moment change (Deltamu = 7.8-8.0 D) for the lowest-energy electronic transition (band I), the electrofluorescence of TAB accompanied the change in the molecular polarizability. The spectroscopic and excited-state properties of TAB including the curious behavior of the electrofluorescence spectrum as mentioned above were discussed on the basis of theoretical considerations.

Journal Article↗

PubMed2005

Spectroscopic and excited-state properties of tri-9-anthrylborane I: Solvent polarity effects.

Spectroscopic and excited-state properties of tri-9-anthrylborane (TAB), showing unique absorption and fluorescence characteristics originating from p(boron)-pi(anthryl group) orbital interactions, were studied in 12 solvents. Although the absorption maximum energy (nu(a)) of TAB which appeared at around 21 x 10(3) cm(-1) (band I) was almost independent of the solvent polarity parameter, f(X) (f(X) = (D(s) - 1)/(2D(s) + 1) - (n(2) - 1)/(2n(2) + 1) where D(s) and n represent the static dielectric constant and the refractive index of a solvent, respectively), the fluorescence maximum energy (nu(f)) showed a linear correlation with f(X). The f(X) dependence of the value of nu(a) - nu(f) demonstrated that the change in the dipole moment of TAB upon light excitation was approximately 8.0 D, indicating that absorption band I was ascribed to an intramolecular charge-transfer transition in nature. The excited electron of TAB was thus concluded to localize primarily on the p orbital of the boron atom. Furthermore, it was shown that the fluorescence lifetime and quantum yield of TAB varied from 11.8 to 1.1 ns and from 0.41 to 0.02, respectively, with an increase in f(X). The present results indicated that the nonradiative decay rate constant (k(nr)) of TAB was influenced significantly by f(X). Excited-state decay of TAB was understood by intramolecular back-electron (charge) transfer from the p orbital of the boron atom to the pi orbital of the anthryl group, which was discussed in terms of the energy gap dependence of k(nr). Specific solvent interactions of TAB revealed by the present spectroscopic and photophysical studies are also discussed.

Journal Article↗

PubMed2005

Template-guided synthesis and individual characterization of poly(N-isopropylacrylamide)-based microgels.

We have succeeded in making cylindrical PNIPA-based microgels by a novel strategy in which template-guided synthesis and photochemical polymerization were combined. Cylindrical PNIPA-based microgels of relatively uniform sizes were easily obtained corresponding to the pore size of the template PC membranes. We have also individually characterized our PNIPA-based microgels by a laser trapping/Raman spectroscopy technique. On the basis of these results, the individual microscopic objects were confirmed to be PNIPA-based microgels.

Journal Article↗

PubMed2005

Poly(N-isopropylacrylamide) microparticles produced by radiation pressure of a focused laser beam: a structural analysis by confocal Raman microspectroscopy combined with a laser-trapping technique.

We developed a confocal Raman microspectroscopy system combined with a laser trapping technique and applied it to aqueous solutions (H(2)O and D(2)O) of poly(N-isopropylacrylamide) (PNIPA), which is well-known as a representative thermo-responsive polymer, i.e., phase transition/separation between coiled and globular states. By introducing a near-infrared (1064 nm) laser beam into a microscope, PNIPA microparticles were produced at the focused spot of the laser beam, both in H(2)O and D(2)O. By using the present system, we succeeded in obtaining the Raman spectra of PNIPA in the coiled and globular states over a wide wavenumber region (800-3500 cm(-1)) for the first time. For the D(2)O solutions (in which the photothermal effect is negligible and hence the microparticles should be produced purely by the effect of radiation pressure), some significant differences were observed in the Raman spectra for the coiled state, in the globular state, and for laser induced microparticles. By analyzing these spectra in detail, we revealed that the structure of the laser-induced microparticles was analogous to that in the globular state. We also discuss the fundamental mechanism underlying the transformation of the higher order structure of a polymer by radiation pressure.

Journal Article↗

PubMed2005

Association of 14-3-3 epsilon gene haplotype with completed suicide in Japanese.

Genetic factors have been suggested to be involved in suicide. Although some genetic factors, such as serotonergic transduction, have been associated with suicide, the results are inconsistent. There is a possibility that various signaling anomalies are involved in the biological vulnerability to suicide. We carried out a genome-wide gene-expression study in the brains of suicide victims using DNA microarrays;14-3-3 epsilon, which is related to neurogenesis, was one of the genes upregulated in the brains of suicide victims in the microarray analysis. This was confirmed by Western blot analysis. To examine the possibility of the involvement of 14-3-3 epsilon in the pathogenesis of suicide, we investigated the association of the 14-3-3 epsilon gene and completed suicide. We used three high-frequency SNPs (rs1532976, rs3752826, and rs9393) and found a significant association of two alleles (rs1532976 and rs3752826) with completed suicide (p < 0.05). Moreover, the distribution of haplotype revealed a more significant difference between completed suicide and controls (p=0.0005). This finding suggests that 14-3-3 epsilon is a potential suicide susceptibility gene and implies that dysregulation of neurogenesis may be involved in suicide.

14-3-3 Proteins↗

PubMed2005

Exacerbation of rheumatoid arthritis following Helicobacter pylori eradication: disruption of established oral tolerance against heat shock protein?

A 62-year-old Japanese woman with RA received an eradication therapy against Helicobacter pylori in November 1999. Eight weeks later, successful eradication was confirmed by negative results for rapid urease test, pathologic findings, and a fall in anti-H. pylori IgG antibody titer. During the course, parameters for RA activity were exacerbated: C-reactive protein 1.1-4.2 mg/dL, rheumatoid arthritis precipitation antigen 2560-5120 dils., erythrocyte sedimentation rate 52-123 mm/h, and complements CH50 50 to over 60 U/mL. Lansbury index increased from 70% to 105%. Two more weeks later, the patient noticed right shoulder pain. She also complained of bilateral gonalgia two months later, and physical examination revealed increased fluid in the knee joints. Prednisolone was required to control the disease activity. The results of this case suggested that RA patients might experience a deleterious effect on the disease activity following H. pylori eradication possibly through disruption of the established oral tolerance against stress protein such as mycobacterial heat shock protein 65.

Administration, Oral↗

PubMed2005

Change of suicidal ideation induced by suicide attempt.

Some studies have reported that a suicide attempt has a cathartic effect. We studied a change of suicidal ideation just before and after a suicide attempt to test whether a cathartic effect exists and, if a cathartic effect does exist, to identify factors that may affect it. Subjects consisted of 88 suicide attempters (29 males, 59 females, mean age=35.5 years) who attended the emergency medical center of Kobe City General Hospital, Kobe, Japan. Strength of suicidal ideation just before and after a suicide attempt was evaluated by 11 steps from 0 to 10, where 0 indicates no suicidal ideation and 10 indicates the strongest suicidal ideation. Subjects were also interviewed about any clinical backgrounds related to suicide attempts. Diagnoses were made by psychiatrists based on ICD-10. Scores of suicidal ideation decreased significantly after the suicide attempt in comparison with those just before the suicide attempt (P<0.0001). In suicide attempters of each generation under 60 years of age, there were significant decreases in scores of suicidal ideation after the suicide attempt, but not in those of over 60 years of age. Scores of suicidal ideation after the suicide attempt were significantly higher in the group of F4 classified by ICD-10 than that of F2. Our results indicate that the cathartic effect induced by suicide attempt is different among generations and psychiatric disorders.

Adolescent↗

PubMed2005

Molecular probe for a fluorous medium: long-lived phosphorescence of alpha-diketones in perfluoromethylcyclohexane at room temperature.

We found that alpha-diketones (2,3-butanedione (BD) and 1-phenyl-1,2-propanedione (PPD)) were very suitable luminescence probes for studying the properties of a perfluorinated solvent (i.e., fluorous solvent; perfluoromethylcyclohexane (PFMC)), since these compounds were soluble in PFMC and showed long-lived phosphorescence even at room temperature. The phosphorescence lifetime (tau(p)) of BD in PFMC (650 micros) was much longer than that in cyclohexane (CH, 270 micros). The longer tau(p) value of BD in PFMC was ascribed to the variation of the intersystem crossing rate constant (k(isc)) from the excited triplet state (T1) to the ground state (S0) with the solvent. Some possible reasons for the change in k(isc) were discussed in terms of solute-solvent interactions. Furthermore, by utilizing phosphorescence quenching of BD by pyrene, we, determined a rate constant of the diffusion-controlled reaction in PFMC. Characteristic behaviors of mixing/separation processes between PFMC and a common organic solvent observed by Schlieren photographs were also reported.

Journal Article↗