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S Tajima

Publications and source records attributed to S Tajima.

At least 55 records · Page 3Linked to original sources
PubMed2001

Enzymatic properties of de novo-type mouse DNA (cytosine-5) methyltransferases.

We have purified GST-fused recombinant mouse Dnmt3a and three isoforms of mouse Dnmt3b to near homogeneity. Dnmt3b3, an isoform of Dnmt3b, did not have DNA methylation activity. Dnmt3a, Dnmt3b1 or Dnmt3b2 showed similar activity toward poly(dG-dC)-poly(dG-dC) for measuring de novo methylation activity, and toward poly(dI-dC)-poly(dI-dC) for measuring total activity. This indicates that the enzymes are de novo-type DNA methyltransferases. The enzyme activity was inhibited by NaCl or KCl at concentrations >100 mM. The kinetic parameter, K(m)(AdoMet), for Dnmt3a, Dnmt3b1 and Dnmt3b2 was 0.4, 1.2 and 0.9 microM when poly(dI-dC)-poly(dI-dC) was used, and 0.3, 1.2 and 0.8 microM when poly(dG-dC)-poly(dG-dC) was used, respectively. The K(m)(DNA) values for Dnmt3a, Dnmt3b1 and Dnmt3b2 were 2.7, 1.3 and 1.5 microM when poly(dI-dC)-poly(dI-dC) was used, and 3.5, 1.0 and 0.9 microM when poly(dG-dC)-poly(dG-dC) was used, respectively. For the methylation specificity, Dnmt3a significantly methylated CpG >> CpA. On the other hand, Dnmt3b1 methylated CpG > CpT >/= CpA. Immuno-purified Dnmt3a, Myc-tagged and overexpressed in HEK 293T cells, methylated CpG >> CpA > CpT. Neither Dnmt3a nor Dnmt3b1 methylated the first cytosine of CpC.

Binding Sites↗
PubMed2001

Evidence of doping-dependent pairing symmetry in cuprate superconductors.

Scanning tunneling spectroscopy studies reveal long-range spatial homogeneity and predominantly d(x(2)-y(2))-pairing spectral characteristics in under- and optimally doped YBa2Cu 3O (7-delta) superconductors, whereas STS on YBa2(Cu 0.9934Zn 0.0026Mg (0.004))3O (6.9) exhibits microscopic spatial modulations and strong scattering near the Zn or Mg impurity sites, together with global suppression of the pairing potential. In contrast, in overdoped (Y 0.7Ca (0.3))Ba 2Cu 3O (7-delta), (d(x(2)-y(2))+s)-pairing symmetry is found, suggesting significant changes in the superconducting ground state at a critical doping value.

Journal Article↗
PubMed2001

Superconducting gap and strong in-plane anisotropy in untwinned YBa2Cu3O(7-delta).

With significantly improved sample quality and instrumental resolution, we clearly identify in the ( pi,0) photoemission spectra from YBa(2)Cu(3)O(6.993), in the superconducting state, the long-sought "peak-dip-hump" structure. This advance allows us to investigate the large a-b anisotropy of the in-plane electronic structure including, in particular, a 50% difference in the magnitude of the superconducting gap that scales with the energy position of the hump feature. This anisotropy, likely induced by the presence of the CuO chains, raises serious questions about attempts to quantitatively explain the YBa(2)Cu(3)O(7-delta) data from various experiments using models based on a perfectly square lattice.

Journal Article↗
PubMed2001

Transverse josephson plasma mode in T* cuprate superconductors.

A transverse optical plasma mode is observed at far-infrared frequencies within the superconducting gap region by measuring the c-axis optical reflectivity for single crystals of T* cuprate superconductors SmLa0.85Sr0.15CuO4-delta and Nd1.4Sr0.4Ce0.2CuO4-delta. These T* cuprates have two different insulating layers sandwiching the superconducting CuO2 planes, leading to two longitudinal plasmons. Also, the transverse mode is directly observed due to the coupling of the infrared radiation with the current perpendicular to the superconducting layers which are regarded as an alternating array of two inequivalent Josephson junctions.

Journal Article↗
PubMed2001

Phase fluctuations and the pseudogap in YBa(2)Cu(3)O (x).

The thermodynamics of the superconducting transition is studied as a function of doping using high-resolution expansivity data of YBa(2)Cu(3)O (x) single crystals and Monte Carlo simulations of the anisotropic 3D- XY model. We directly show that T(c) of underdoped YBa(2)Cu(3)O (x) is strongly suppressed from its mean-field value (T(MF)(c)) by phase fluctuations of the superconducting order parameter. For overdoped YBa(2)Cu(3)O (x) fluctuation effects are greatly reduced and T(c) approximately T(MF)(c). We find that T(MF)(c) exhibits a similar doping dependence as the pseudogap energy, naturally suggesting that the pseudogap arises from phase-incoherent Cooper pairing.

Journal Article↗
PubMed2001

c-axis optical response in the static stripe ordered phase of the cuprates.

The c-axis far-infrared reflectivity spectra in the superconducting state were investigated for La1.85-yNd(y)Sr0.15CuO4. The Josephson plasma edge rapidly shifts towards lower frequency with increasing y, and almost disappears when y exceeds a critical value ( y(c) approximately 0.12) above which the low-temperature-tetragonal (LTT) deformation switches on, stabilizing the spin/charge ordered stripe phase. In the vicinity of y(c), a "normal state" reentrant behavior was observed with lowering temperature below Tc. This clearly demonstrates that the static stripe order pinned by the LTT distortion suppresses the interlayer phase coherence.

Journal Article↗
PubMed2001

Metastable ion study of organosilicon compounds. Part XIII: dimethoxydimethylsilane, (CH(3))(2)Si(OCH(3))(2), and dimethoxymethylsilane, CH(3)SiH(OCH(3))(2).

Unimolecular metastable fragmentations of dimethoxydimethylsilane, (CH(3))(2)Si(OCH(3))(2) (MW 120, 1), and dimethoxymethylsilane, CH(3)SiH(OCH(3))(2) (MW 106, 2), upon electron impact ionization have been studied by means of mass-analyzed ion kinetic energy (MIKE) spectrometry and the D-labeling technique in conjunction with thermochemistry. The results have been compared with those of the corresponding carbon analogues, 2,2-dimethoxypropane, (CH(3))(2)C(OCH(3))(2) (MW 104, 3) and 1,1-dimethoxyethane, CH(3)CH(OCH(3))(2) (MW 90, 4). In analogy with the cases of 3 and 4, both molecular ions from 1 and 2 are formed at very low abundance at 70 eV, and begin to decompose by the expulsion of the substituents (H, CH(3) or OCH(3)) on the central silicon atom. These decompositions are followed by the loss of a formaldehyde molecule (CH(2)O), as commonly observed in the mass spectra of methoxysilanes. Further, an ethylene (C(2)H(4)) or a dimethyl ether (CH(3)OCH(3)) molecule loss is observed in the fragmentation of some intermediate ions generated from 1(+)* and 2(+)*, but the mechanisms are different than those in the cases of 3 and 4. Some of these fragmentations are also different than those reported previously. The relative abundance of the ions in many MIKE spectra is explained by the extension of the Stevenson-Audier rule. The reaction, which is in contrast to the rule, however, is rationalized by the energy of the transition state for the reaction, estimated by semi-empirical molecular orbital calculation. The peak at m/z 59 from 2(+)* consists only of CH(3)OSi(+) ion, whereas the peak from 1(+)* consists of two different ions, CH(3)OSi(+) and (CH(3))(2)Si(+)H. The ions CH(3)OSi(+) from 1(+)* and 2(+)* are generated by at least two and three separate routes respectively.

Journal Article↗
PubMed2001

Immunohistochemical detection of lipid peroxidation products, protein-bound acrolein and 4-hydroxynonenal protein adducts, in actinic elastosis of photodamaged skin.

Acrolein and 4-hydroxy-2-nonenal (HNE) are both byproducts of a lipid peroxidation reaction. Actinic elastosis in photodamaged skin of aged individuals is characterized by the accumulation of fragmented elastic fibers in the sun-exposed areas. To study whether a lipid peroxidation reaction is involved in the accumulation of altered elastic fibers in actinic elastosis, skin specimens obtained from sun-damaged areas were immunohistochemically examined using the antibodies against acrolein and HNE. Both antibodies were found to react with the accumulations of elastic material. Double immunofluorescence labeling demonstrated that acrolein/elastin and HNE/elastin were colocalized in the actinic elastosis. Western blot analysis showed that the polypeptide with a molecular weight of 62 kDa reacted with anti-acrolein, anti-HNE and anti-elastin antibodies. The results suggest that acrolein and HNE may be associated with actinic elastosis.

Acrolein↗
PubMed2001

In vitro and in vivo expression of protoporphyrin IX induced by lipophilic 5-aminolevulinic acid derivatives.

We estimated the expression level of protoporphyrin IX (PpIX) induced by lipophilic 5-aminolevulinic acid (ALA) derivatives and observed its histological distribution by fluorescence microscopy. In vitro PpIX expression in Hepe2 cells was the highest when induced by ALA pentyl ester. This level was 2.8-fold higher than that induced by ALA after 4 h incubation and 2.5-fold higher than that after 24 h incubation. The differences between ALA pentyl ester and ALA were significant at both time points (P<0.01). In HeLa cells, ALA butyl ester showed the highest induction of PpIX, which was 2.6-fold higher than ALA after 4 h incubation and 3.5-fold higher after 24 h incubation. The differences were significant at both time points (P<0.01). In mice with squamous cell carcinoma, the in vivo expression of PpIX in the tumors was highest with ALA methyl ester, which was 1.3-fold higher than ALA. The difference was significant (P<0.01). The expression of PpIX by means of fluorescence microscopy was highest by ALA methyl ester. Under in vitro conditions, PpIX expression was efficiently induced by long chain ALA esters, while better in vivo PpIX induction was obtained with short chain ALA esters. In this study, ALA methyl ester was found to be the best among the ALA derivatives in inducing PpIX expression in vivo, and would be more effective in treatment of skin cancers than ALA.

Aminolevulinic Acid↗
PubMed2001

Co-ordinated induction of beta-carotene cleavage enzyme and retinal reductase in the duodenum of the developing chicks.

The developmental patterns of expression of beta-carotene cleavage enzyme activity were compared with those of retinal reductase and NAD-dependent retinol dehydrogenase activities in chick duodenum during the perinatal period. The beta-carotene cleavage enzyme activity was not detected in the duodenum before hatching, but it increased rapidly during 24 h after hatching. On the other hand, a considerable level of beta-carotene cleavage enzyme activity was observed in the liver of embryonic stages and its activity gradually rose during the perinatal period. Comparison of kinetic constants for the beta-carotene cleavage enzyme activities in the duodenum and the liver indicated that the enzyme in the duodenum possessed a lower affinity for beta-carotene than that in the liver. The retinal reductase activity was detected in the microsomes of the duodenum at the earliest time examined, i.e. day 16 of embryogenesis and its activity began to rise on the last day of embryogenesis, which was followed by a gradual increase until 1 day of age. The NAD-dependent retinol dehydrogenase activity was also seen in the microsomes of the duodenum in embryonic stages and its activity increased in parallel with the retinal reductase activity around the hatching period. These developmental inductions of beta-carotene cleavage enzyme and retinal reductase activities in the duodenum coincided with those of cellular retinol-binding protein, type II (CRBPII) and lecithin: retinol acyltransferase (LRAT). These results suggest that a co-ordinated induction mechanism should be operative for beta-carotene cleavage enzyme and retinal reductase, both of which are inevitable in the process of beta-carotene absorption and metabolism.

Acyltransferases↗
PubMed2001

Photodynamic therapy of acne vulgaris with topical delta-aminolaevulinic acid and incoherent light in Japanese patients.

BACKGROUND: Photodynamic therapy (PDT) is useful for treatment of epidermal neoplasia but may also have a role in the treatment of inflammatory dermatoses. OBJECTIVES: To study the effect of PDT in patients with acne. METHODS: Three men and 10 women who suffered from intractable acne vulgaris were treated using PDT with topical delta-aminolaevulinic acid (ALA) and polychromatic visible light. Twenty per cent ALA in an oil-in-water emulsion was applied to the lesions for 4 h with a light-shielding dressing. The lesions were then exposed to polychromatic visible light at 600-700 nm using a halogen light source of energy intensity 17 mW cm-2 and a total energy dose of 13 J cm-2. RESULTS: All patients had apparent improvement of facial appearance and reduction of new acne lesions at 1, 3 and 6 months following PDT treatment. The adverse effects were discomfort, burning and stinging during irradiation, oedematous erythema for 3 days after PDT, epidermal exfoliation from the fourth to the 10th day, irritation and hypersensitivity to physical stimulation for 10 days after PDT, and pigmentation or erythema after epidermal exfoliation; the treated lesions returned to normal skin conditions within 1 month. CONCLUSIONS: PDT was beneficial in the treatment of acne. As a photoactivating light source, polychromatic visible light was thought to be better for use with acne patients than laser light because of its cost-effectiveness, uniform illumination and time-efficiency in treating large areas.

Acne Vulgaris↗
PubMed2001

Reticular erythematous mucinosis syndrome with an infiltration of factor XIIIa+ and hyaluronan synthase 2+ dermal dendrocytes.

We report a patient with reticular erythematous mucinosis (REM) syndrome. Content of hyaluronan in lesional skin was approximately 2.9-fold higher than in the patient's uninvolved skin, but its synthetic activity in fibroblasts explanted from lesional skin remained unchanged. Immunohistochemical study using antifactor XIIIa (anti-FXIIIa) antibody demonstrated that the number of FXIIIa+ cells in the lesional skin was significantly increased compared with those in the patient's uninvolved skin and in normal control skin samples (P < 0.01). As hyaluronan is considered to be synthesized by hyaluronan synthase (HAS), which is composed of three genetically distinct isoforms (HAS1, HAS2 and HAS3), the cells responsible for the accumulation of hyaluronan in lesional skin were immunohistochemically examined using antibodies for HAS1, HAS2 and HAS3. The specific antibody for HAS2 was found to react with some populations of FXIIIa+ cells in the involved skin, and the number of HAS2+ cells was significantly increased in the involved skin (P < 0.01). The results suggest that accumulation of hyaluronan in REM may be related to populations of FXIIIa+/HAS2+ dermal dendrocytes rather than to dermal fibroblasts.

Cell Culture Techniques↗
PubMed2001

Indomethacin induced bulky lymphadenopathy and eosinophilic pneumonia.

Indomethacin is one of the most popular non-steroidal anti-inflammatory drugs (NSAID). Although NSAID occasionally provoke bronchospasm and hypersensitivity pneumonia, they seldom cause lymphadenopathy. This is the first report in which NSAID induced both eosinophilic pneumonia and bulky intrathoracic lymphadenopathy simultaneously. A 76-year-old Japanese man experienced high fever and dyspnoea after using an indomethacin suppository. Computed tomography scan of his chest revealed massive mediastinal and hilar lymphadenopathy along with diffuse infiltration in both lungs. He was diagnosed to have eosinophilic pneumonia because of eosinophilia in his peripheral blood and bronchoalveolar lavage fluid (BALF). Without using glucocorticoids, the pulmonary infiltration and lymphadenopathy subsided spontaneously. As the blastoid transformation test using the lymphocytes in his BALF was positive to indomethacin, we judged that both his eosinophilic pneumonia and mediastinal lymphadenopathy were due to a hypersensitivity reaction to indomethacin. An allergic reaction to NSAID should be considered as a rare cause of mediastinal lymphadenopathy.

Aged↗
PubMed2001

Pulmonary intravascular lymphoma complicated with Pneumocystis carinii pneumonia: a case report.

We report a case of intravascular lymphoma (IVL) complicated with Pneumocystis carinii pneumonia (PCP). A 65-year-old male complaining of dyspnea and dementia was diagnosed to have pulmonary IVL by transbronchial lung biopsy. Concomitantly, deoxyribonucleic acid sequence specific to Pneumocystis carinii was detected in bronchoalveolar lavage fluid by polymerase chain reaction. Differential responses to the sequential treatments for PCP and IVL implied that increased serum lactate dehydrogenase (LDH) was due to PCP, whereas hypoxemia and dementia were due to IVL. Although pulmonary IVL and PCP share many clinical presentations, exact diagnosis is essential for their successful treatment.

Aged↗
PubMed2001

Xenopus eggs express an identical DNA methyltransferase, Dnmt1, to somatic cells.

In mouse, an oocyte-specific short isoform of DNA methyltransferase-1 (Dnmt1) lacking amino terminal 118 amino acid residues exists and plays a crucial role in maintaining the methylation state of imprinted genes during early embryogenesis [Howell et al. (2001) Cell 104, 829-838]. To address the question of whether or not Xenopus oocyte expresses such a short isoform, we raised monoclonal antibodies against the amino-terminal portion of Xenopus Dnmt1. Two of the isolated monoclonal antibodies, 3C6 and 4A8, were determined to recognize (1-32) and (115-126) of Xenopus Dnmt1, respectively. The amounts of Dnmt1 in Xenopus eggs were determined to be similar, 10.0 2.5, 8.0 0.8, and 8.2 0.2 ng per egg with monoclonal antibodies 3C6 and 4A8, and polyclonal antibodies, respectively. This indicated that Dnmt1 in Xenopus mature eggs had an identical amino-terminal sequence to the amino acid sequence deduced from the cDNA. Together with the fact that Dnmt1 in A6 cells immuno-reacted with all the monoclonal antibodies isolated and with the polyclonal antibodies, we concluded that Dnmt1 expressed in Xenopus mature eggs possesses an identical amino-terminal sequence to that in somatic cells. Immuno-purified Xenopus Dnmt1 in mature eggs showed similar specific activity to that in proliferating A6 cells and that of mouse recombinant Dnmt1.

Amino Acid Sequence↗
PubMed2001

Mandibular contour reconstruction with three-dimensional computer-assisted models.

Facial contours are thought to depend on the appropriate balance of hard and soft tissue. To obtain aesthetically good results in head and neck reconstruction, surgeons should know the exact three-dimensional shape and volume of both hard and soft tissue to be reconstructed. The authors used computer-assisted three-dimensional solid models of the mandible in 7 patients (4 women and 3 men) who underwent mandibular contour reconstruction. Scapular osteocutaneous flaps were used in all 7 patients. The follow-up periods ranged from 7 to 57 months (mean follow-up, 29 months). No flap was lost. One patient died of metastatic cancer. In 2 patients the aesthetic results were excellent and in 4 patients they were good. Computer-assisted three-dimensional models for mandibular contour reconstruction in head and neck reconstruction are quite useful.

Adolescent↗