PubMed Health⌕ Search

Biomedical subjects

Masayuki Endo

Publications and source records attributed to Masayuki Endo.

At least 19 recordsLinked to original sources
PubMed2006

Detection of the local structural changes in the dimer interface of BamHI initiated by DNA binding and dissociation using a solvatochromic fluorophore.

To detect the local structural change in an interface between proteins induced by the substrate binding and dissociation, a solvatochromic fluorescent N(beta)-L-alanyl-5-(N,N-dimethylamino)-naphthalene-1-sulfonamide (DanAla) was introduced into 132 position of the dimer interface in BamHI. Before addition of the substrate, the fluorescence from the normal planer excited state of DanAla moiety was observed as a main emission, and thereby the DanAla in the dimer interface is located in the hydrophobic microenvironment. The incubation with the substrate for 20 min induced the gradual increase in fluorescence intensity around 430 nm. The fact reflects that the polarity is reduced by the slight structural change initiated by the formation of the complex with the substrate. Furthermore, the incubation for more than 20 min caused the slight decrease in fluorescence around 430 nm and an appearance of fluorescence (560 nm) due to twisted intramolecular charge transfer (TICT) excited state. Therefore, the DanAla is exposed to comparative polar environment after the dissociation of the substrate. The fluorescence lifetime as a minor component, which is attributed to the TICT excited state, was reduced by addition of the substrate. The results provide that the hydrophobicity in the dimer interface is increased by the substrate binding. Interestingly, we found that the structure of an initial form is different from that of a refolded form after the dissociation of the substrate using a spectral subtraction technique. We have achieved detection of the changing structure induced by the substrate binding and dissociation using a steady-state and time-resolved fluorescence.

DNA↗
PubMed2006

Evidence for an immune barrier after in utero hematopoietic-cell transplantation.

The competence of the immune system of the developing fetus to act as a barrier to in utero hematopoietic-cell transplantation (IUHCT) has been a source of debate. Until now, comparisons of allogeneic and congenic engraftment have been inconclusive due to methodologic limitations resulting in minimal and inefficient engraftment. In this study, E14 fetal mice received transplants of either allogeneic or congenic bone marrow using a new intravascular technique that allows definitive administration of much higher doses of donor cells. Our results demonstrate that 100% of surviving recipients demonstrate engraftment at 1 week of age, but that 70% of allogeneic recipients lose engraftment by 1 month of age, and 80% ultimately fail to sustain long-term chimerism. In contrast, all congenic recipients maintain stable, long-term, multilineage chimerism. These results strongly support an immune barrier to allogeneic engraftment after IUHCT.

Animals↗
PubMed2006

CD26 inhibition enhances allogeneic donor-cell homing and engraftment after in utero hematopoietic-cell transplantation.

In utero hematopoietic-cell transplantation (IUHCT) can induce donor-specific tolerance to facilitate postnatal transplantation. Induction of tolerance requires a threshold level of mixed hematopoietic chimerism. CD26 is a peptidase whose inhibition increases homing and engraftment of hematopoietic cells in postnatal transplantation. We hypothesized that CD26 inhibition would increase donor-cell homing to the fetal liver (FL) and improve allogeneic engraftment following IUHCT. To evaluate this hypothesis, B6GFP bone marrow (BM) or enriched hematopoietic stem cells (HSCs) were transplanted into allogeneic fetal mice with or without CD26 inhibition. Recipients were analyzed for FL homing and peripheral-blood chimerism from 4 to 28 weeks of life. We found that CD26 inhibition of donor cells results in (1) increased homing of allogeneic BM and HSCs to the FL, (2) an increased number of injected animals with evidence of postnatal engraftment, (3) increased donor chimerism levels following IUHCT, and (4) a competitive engraftment advantage over noninhibited congenic donor cells. This study supports CD26 inhibition as a potential method to increase the level of FL homing and engraftment following IUHCT. The resulting increased donor chimerism suggests that CD26 inhibition may in the future be used as a method of increasing donor-specific tolerance following IUHCT.

Animals↗
PubMed2006

Pyrene-stacked nanostructures constructed in the recombinant tobacco mosaic virus rod scaffold.

The effect of pyrenes introduced into a tobacco mosaic virus (TMV) coat protein monomer on the formation and stability of the TMV assembly was investigated. The possible arrangement of the pyrenes in the inner cavity of the TMV rod was also estimated. The pyrene derivative was introduced to four specific amino acids in the cavity of the TMV rod structure. Rod-structure formation was examined by atomic force microscopy (AFM). Two pyrene-attached mutants (positions 99 and 100) assembled to increase the length of the rod structures by 2.5 microm at pH 5.5. The interaction of the pyrene moieties in the TMV cavity was investigated by steady-state and time-resolved spectroscopic analysis. Strong excimer emission with significantly short wavelength (465 nm) was observed from the two mutants mentioned above. Excitation and UV-visible spectra indicate that the pyrene moieties form pi-stacked structures in the TMV cavity. Details of the pyrene interaction were investigated by analyzing the fluorescence lifetime of the excimer. Results suggest that the pyrenes formed preassociated rigid structures with partially overlapped geometry in the restricted space of the TMV cavity. The pyrenes effectively stabilize the TMV rod through a pi-stacking interaction in a well-ordered way, and the single pyrene moiety introduced into the monomer affects the overall formation of the TMV rod structure.

Capsid Proteins↗
PubMed2006

[Case of rheumatoid arthritis with various histological lesions of the kidney].

We experienced a case of rheumatoid arthritis with nephrotic syndrome. A renal biopsy specimen from this patient showed various renal histological changes. The patient was a 50-year-old man who was diagnosed as having rheumatoid arthritis in 1987. We performed a renal biopsy because he had persistent proteinuria from March in 2002. The renal biopsy specimen showed amyloid AA and P protein deposition in the glomeruli. Moreover mild mesangial proliferation was recognized. IgA-deposition in the mesangial area, and granular-deposition of IgG along the glomerular capillary wall were also observed. In electron microscopy, electron dense deposits were recognized in the mesangial area and subepithelium of the glomerular basement membrane. From these findings, we diagnosed amyloid nephropathy, IgA nephritis and membranous nephropathy. Renal biopsy of patients with RA is useful not only for precise diagnosis, but also for selection of the appropriate treatment.

Amyloid Neuropathies↗
PubMed2005

Site-specific fluorescent labeling of RNA molecules by specific transcription using unnatural base pairs.

Site-specific fluorescent labeling of RNA molecules was achieved by specific transcription using an unnatural base pair system. The unnatural base pairs between 2-amino-6-(2-thienyl)purine (s) and 2-oxo(1H)pyridine (y), and 2-amino-6-(2-thiazolyl)purine (v) and y function in transcription, and the substrates of y and 5-modified y bases can be site-specifically incorporated into RNA, opposite s or v in DNA templates, by T7 RNA polymerase. Ribonucleoside 5'-triphosphates of 5-fluorophore-linked y bases were chemically synthesized from the nucleoside of y. These fluorescent substrates were site-specifically incorporated into RNA by transcription mediated by the s-y and v-y pairs. By using this fluorescent labeling method, specific positions of Raf-binding and theophylline-binding RNA aptamers were fluorescently labeled, and the specific binding to their target molecules was detected by their fluorescent intensities. This site-specific labeling method using an unnatural base pair system will be useful for analyzing conformational changes of RNA molecules and for detecting interactions between RNA and its binding species.

Aptamers, Nucleotide↗
PubMed2005

Four-way-branched DNA-porphyrin conjugates for construction of four double-helix-DNA assembled structures.

[reaction: see text] DNA-porphyrin conjugates having four DNA strands were designed and synthesized. Four double helices were assembled using two DNA-porphyrin conjugates and their complementary strands, and the formation of the four double-helix assembled structures with the two DNA-porphyrin units was examined by gel electrophoresis and spectroscopic analysis. The interaction between two porphyrin chromophores in the complex was investigated by measurement of fluorescence lifetimes, and the singlet energy transfer between the two different phorphyrin units (Zn-porphyrin and H2-porphyrin) was observed. These results indicate that multiple and different porphyrin chromophores can be integrated into the DNA structures by programming the sequences of the DNA strands.

DNA↗
PubMed2005

Structural arrangement of DNA constrained by a cross-linker.

Self-complementary cross-linked oligonucleotides with a disulfide linkage were designed and synthesized. Double helix and hairpin structures were controlled using the different diastereochemistry of phosphoramidate where the cross-linker was introduced. The structures of the strained cross-linked DNAs were estimated by gel mobility, circular dichroism spectra, and melting profiles.

Amides↗
PubMed2005

Stepwise photocleavage of C-O bonds of bis(substituted-methyl)naphthalenes with stepwise excitation by two-color two-laser and three-color three-laser irradiations.

Stepwise photocleavage of naphthylmethyl-oxygen (C-O) bonds of mono(substituted-methyl)naphthalenes [1- and 2-ROCH2Np, R = 4-benzoylphenyl (BP), phenyl (Ph), and methyl (CH3)] and bis(substituted-methyl)naphthalenes [1,8-(ROCH2)2Np and 1,4-(ROCH2)2Np, R = BP and Ph] was observed to give the naphthylmethyl radicals (NpCH2* or ROCH2NpCH2*) in almost 100% yield with two-step or three-step excitation by the two-color two-laser or three-color three-laser irradiation, respectively, at room temperature. The C-O bond cleavage quantum yields of 1-PhOCH2Np, 2-PhOCH2Np, 1,8-(PhOCH2)2Np, and 1,4-(PhOCH2)2Np were higher than those of 1-BPOCH2Np, 2-BPOCH2Np, 1,8-(BPOCH2)2Np, and 1,4-(BPOCH2)2Np. No C-O bond cleavage occurred from 1,8-(HOCH2)2Np and 2-CH3OCH2Np in the higher triplet excited state (T(n)). The experimental results show that the C-O bond cleavage was determined not only by the position of the substituents on Np but also by the type of the substituents. The C-O bond cleavage of 1-ROCH2Np was more efficient than that of 2-ROCH2Np. In the case of 1,8-(ROCH2)2Np and 1,4-(ROCH2)2Np (R = BP and Ph), the first C-O bond cleavage from the T(n) states occurred to give ROCH2-substituted naphthylmethyl radicals (1,8- and 1,4-ROCH2NpCH2*) when the T1 states, generated with the 308-nm first laser irradiation, were excited using the 430-nm second laser. The second C-O bond cleavage occurred when 1,8- and 1,4-ROCH2NpCH2* in the ground state [1,8- and 1,4-ROCH2NpCH2*(D0)] were excited to the excited states [1,8- and 1,4-ROCH2NpCH2*(D(n))] using the third 355-nm laser during the three-color three-laser flash photolysis at room temperature. It was revealed that acenaphthene was produced as the final product during the stepwise C-O bond cleavages of 1,8-(BPOCH2)2Np and 1,8-(PhOCH2)2Np. This is a successful example of stepwise cleavage of two equivalent C-O bonds in a molecule using the three-color three-laser photolysis method.

Journal Article↗
PubMed2005

Dihydrophenanthrene-type intermediates during photoreaction of trans-4'-benzyl-5-styrylfuran.

[structure: see text] Photoreaction of trans-4'-benzyl-5-styrylfuran (trans-BSF) has been studied by the 355-nm laser flash photolysis (LFP) in CH2Cl2 using a Nd3+:YAG laser (30 ps, 5 mJ pulse(-1) or 5 ns, 30 mJ pulse(-1)). Transient fluorescence and absorption spectra assigned to the singlet excited trans-BSF were observed during the 30-ps LFP, whereas a transient absorption spectrum with two peaks at 400 and 510 nm, assigned to the trans-fused dihydrophenanthrene (DHP)-type intermediate (DP1), was observed during the 5-ns LFP. It is clearly suggested that a two-photon absorption process is involved in the formation of DP1. The first photoreaction is the photoisomerization of trans-BSF, which occurs to give cis-BSF. The second photoreaction process is photocyclization of cis-BSF, which occurs to give DP1 decaying with the half lifetime (tau1/2) of 2.8-4.0 micros to produce another DHP-type intermediate (DP2) with an absorption peak at 400 nm in the absence of O2, through [1,9]-hydrogen shift. DP2 decayed with tau1/2 > 500 micros to give the product through aromatization. In O2-saturated CH2Cl2, DP1 decayed with tau1/2 = 250 ns to give a radical intermediate (X) with two peaks at 410 and 510 nm, through hydrogen abstraction of DP1 by O2. X decayed with tau1/2 = 150 micros to give the product through successive hydrogen abstraction.

Journal Article↗
PubMed2005

Inhibition of the formation and decay of stilbene core radical cations by the dendron during the photoinduced electron transfer.

Formation and decay processes of stilbene core radical cation (ST*+) during the photoinduced electron transfer have been studied for a series of stilbene bearing benzyl ether-type dendrons (D). ST*+ and the radical cation of peripheral dendron (D*+) were generated by intermolecular hole transfer from biphenyl radical cation, which was generated from photoinduced electron transfer from biphenyl to the singlet-excited 9,10-dicyanoanthracene in a mixture of acetonitrile and 1,2-dichloroethane (3:1). An intramolecular dimer radical cation of benzyl groups at the terminal of stilbene dendrimer was indicated as a hole trapping site. Subsequent hole transfer from the trapping site to the core ST generated ST*+. The shielding effects of D depending on the dendrimer generation on the growth and decay of ST*+ were observed. It was revealed for the first time that D acts as the hole trapping site and the hole conductor on the way of the exothermic hole transfer from the terminal of D to the central core ST. We also found that D inhibits the charge recombination with 9,10-dicyanoanthracene radical anion because of the steric hindrance.

Journal Article↗
PubMed2005

[An investigation of TS-1 single-agent therapy administered as first-line therapy for unresectable advanced gastric cancer].

We report an investigation of the therapeutic efficacy and safety of TS-1 single-agent therapy administered as first-line therapy in 23 cases of unresectable advanced gastric cancer treated at our institution. TS-1 was administered at 80 mg-120 mg (divided into two doses) per day for 28 days followed by a 14-day rest interval, making up a single cycle. The response rate for its antitumor efficacy was 39.1%, with partial response in nine cases, no change in seven cases, progressive disease in five cases, and two cases not evaluable (9 5% confidence interval: 19.7%-61.5%). By site, the response rate was 43.5% for primary tumors (10/23), 33.3% for lymph nodes (3/9), and 16.7% for liver metastasis (1/6). In 1 patient, the carcinomatous ascites disappeared,and in 3 patients they decreased remarkably. No significant differences were observed with regard to age (70 and over/under 70) or histological type (differentiated/undifferentiated). The one-year survival rate was 32.8%, and the 50% survival period was 29 9 days. The most common side effect was leucopenia in seven cases (30.4%), followed by decreased hemoglobin, loss of appetite, hepatic dysfunction and the like. Most side effects, however, were mild and did not exceed grade 2; grade 3 side effects were seen only in two cases (8.7%) of leucopenia and two (8.7%) of hepatic dysfunction, a low rate of occurrence. The outpatient follow-up ratio(outpatient period/total treatment period) was high at 69.6%, meaning that first-line single-agent therapy with TS-1 is beneficial in terms not only of efficacy but also in maintaining quality of life.

Adult↗
PubMed2004

Effects of benzyl ether type dendrons as hole-harvesting antennas, and shielding for the neutralization of stilbene core radical cations with chloride ion during two-photon ionization of stilbene dendrimers having stilbene core and benzyl ether type dendrons.

The two-photon ionization (TPI) process (308 and 266 nm) of stilbene dendrimers having a stilbene core and benzyl ether type dendrons has been investigated in an acetonitrile and 1,2-dichloroethane mixture (3:1) in order to elucidate the dendrimer effects. The quantum yield of the formation of stilbene core radical cation during the 308-nm TPI was independent of the dendron generation of the dendrimers, whereas a generation dependence of the quantum yield of the radical cation was observed during the 266-nm TPI, where both the stilbene core and benzyl ether type dendron were ionized, suggesting that the subsequent hole transfer occurs from the dendron to the stilbene core, and that the dendron acts as a hole-harvesting antenna. The neutralization rate of the stilbene core radical cation with the chloride ion, generated from the dissociative electron capture by 1,2-dichloroethane, decreased with the increase in the dendrimer generation, suggesting that the dendron is an effective shield of the stilbene core radical cation against the chloride ion.

Journal Article↗