Biomedical subjects

Takeshi Yamada

Publications and source records attributed to Takeshi Yamada.

At least 37 records · Page 2Linked to original sources

PubMed2006

Lupane and oleanane triterpenoids from the cones of Liquidamber styraciflua.

A new lupane- (1) and a new oleanane-type (2) triterpenoid, together with a known compound, massagenic acid G, were isolated from the cones of Liquidamber styraciflua. The structures of 1 and 2 were determined as 6beta,30-dihydroxy-3-oxolup-20(29)-en-28-oic acid and 3alpha-hydroxy-11-oxoolean-12-en-28-oic acid, respectively, on the basis of spectroscopic methods and chemical conversion. Compound 1 and several structural analogues were evaluated for cytotoxicity against the P388 (murine lymphocyte leukemia) and the A549 (human lung cancer) cell lines.

Animals↗

PubMed2006

Cell-adhesion inhibitors produced by a sea hare-derived Periconia sp. II. Absolute stereostructures of peribysins H and I.

Peribysins H (1) and I (2) have been isolated from a strain of Periconia byssoides originally separated from the sea hare Aplysia kurodai. Their absolute stereostructures have been elucidated on the basis of spectroscopic analyses using ID and 2D NMR techniques and some chemical transformations including the modified Mosher's method. These metabolites inhibited the adhesion of human-leukemia HL-60 cells to HUVEC.

Animals↗

PubMed2006

Anaerolinea thermolimosa sp. nov., Levilinea saccharolytica gen. nov., sp. nov. and Leptolinea tardivitalis gen. nov., sp. nov., novel filamentous anaerobes, and description of the new classes Anaerolineae classis nov. and Caldilineae classis nov. in the bacterial phylum Chloroflexi.

One thermophilic (strain IMO-1(T)) and two mesophilic (strains KIBI-1(T) and YMTK-2(T)) non-spore-forming, non-motile, Gram-negative, multicellular filamentous micro-organisms, which were previously isolated as members of the tentatively named class 'Anaerolineae' of the phylum Chloroflexi, were characterized. All isolates were strictly anaerobic micro-organisms. The length of the three filamentous isolates was greater than 100 microm and the width was 0.3-0.4 microm for strain IMO-1(T), 0.4-0.5 microm for strain KIBI-1(T) and thinner than 0.2 microm for strain YMTK-2(T). Strain IMO-1(T) could grow at pH 6.0-7.5 (optimum growth at pH 7.0). The optimal temperature for growth of strain IMO-1(T) was around 50 degrees C (growth occurred between 42 and 55 degrees C). Growth of the mesophilic strains KIBI-1(T) and YMTK-2(T) occurred at pH 6.0-7.2 with optimal growth at pH 7.0. Both of the mesophilic strains were able to grow in a temperature range of 25-50 degrees C with optimal growth at around 37 degrees C. Yeast extract was required for growth of all three strains. All the strains could grow with a number of carbohydrates in the presence of yeast extract. The G + C contents of the DNA of strains IMO-1(T), KIBI-1(T) and YMTK-2(T) were respectively 53.3, 59.5 and 48.2 mol%. Major fatty acids for thermophilic strain IMO-1(T) were anteiso-C(17 : 0), iso-C(15 : 0), C(16 : 0) and anteiso-C(15 : 0), whereas those for mesophilic strains KIBI-1(T) and YMTK-2(T) were branched C(14 : 0), iso-C(15 : 0), C(16 : 0) and branched C(17 : 0), and branched C(17 : 0), C(16 : 0), C(14 : 0) and C(17 : 0), respectively. Detailed phylogenetic analyses based on their 16S rRNA gene sequences indicated that the isolates belong to the class-level taxon 'Anaerolineae' of the bacterial phylum Chloroflexi, which for a long time had been considered as a typical uncultured clone cluster. Their morphological, physiological, chemotaxonomic and genetic traits strongly support the conclusion that these strains should be described as three novel independent taxa in the phylum Chloroflexi. Here, Anaerolinea thermolimosa sp. nov. (type strain IMO-1(T) = CM 12577(T) = DSM 16554(T)), Levilinea saccharolytica gen. nov., sp. nov. (type strain KIBI-1(T) = JCM 12578(T) = DSM 16555(T)) and Leptolinea tardivitalis gen. nov., sp. nov. (type strain YMTK-2(T) = JCM 12579(T) = DSM 16556(T)) are proposed. In addition, we formally propose to subdivide the tentative class-level taxon 'Anaerolineae' into Anaerolineae classis nov. and Caldilineae classis nov. We also propose the subordinate taxa Anaerolineales ord. nov., Caldilineales ord. nov., Anaerolineaceae fam. nov. and Caldilineaceae fam. nov.

Chloroflexi↗

PubMed2006

Atrial electrophysiological abnormality in patients with Brugada syndrome assessed by P-wave signal-averaged ECG and programmed atrial stimulation.

BACKGROUND: There is evidence that some patients with Brugada syndrome (BS) exhibit atrial tachyarrhythmias including paroxysmal atrial fibrillation. We investigated whether BS associated not only with vulnerability to ventricular fibrillation, but also with vulnerability to atrial fibrillation. METHODS AND RESULTS: In 15 patients with BS and Brugada-type electrocardiogram (ECG) (14 men, 1 woman; age 52.8+/-12.9 years) and 15 age-matched control patients (12 men, 3 women; age 50.9+/-18.9 years), the P-wave signal-averaged ECG was recorded, and the filtered P-wave duration was derived from the vector magnitude obtained by X, Y, Z leads. In 11 of the 15 patients with BS and Brugada-type ECG, invasive electrophysiologic testing was conducted. Filtered P-wave duration was significantly increased in patients with BS and Brugada-type ECG in comparison with control subjects (143.2+/-12.9 vs 129.6+/-10.1 ms, p<0.001). Ventricular late potential (root mean square voltage <20 muV in the last 40 ms and <40 muV at a low amplitude signal duration >38 ms) was present in 10 of the 12 BS patients in whom a QRS wave signal-averaged electrogram was also recorded. In all 11 patients with Brugada-type ECG who underwent electrophysiologic testing, sustained atrial fibrillation (>5 min) was induced by 1 or 2 atrial extrastimuli. In 10 of these 11 patients, ventricular fibrillation was also induced by 2 or 3 right ventricular extrastimuli. CONCLUSIONS: The electrical abnormality in BS is not limited to the ventricular level; similar changes occur in the atria. Such abnormal conduction properties could be a substrate for re-entrant atrial tachyarrhythmias.

Adult↗

PubMed2006

[Correlation between clinical pathologic factors and enzymatic activity of orotate Phosphoribosyl transferase (OPRT), Dihydropyrimidine dehydrogenase (DPD) and Thymidylate synthase (TS) in colorectal cancer].

Orotate Phosphoribosyl Transferase (OPRT), Dihydropyrimidine dehydrogenase (DPD) and Thymidylate synthase (TS) are initial key enzymes in the 5-FU metabolic pathway. In this study, we measured the activities of OPRT, DPD and TS. We also investigated the correlation between these 3 enzymatic activities and the clinical pathologic factors (Histological typing, extent of tumor invasion,extent of metastasis to the lymph nodes,stage, lymphatic invasion and venous invasion). We had surveyed 79 cases of colorectal cancers surgically removed. Poorly-differentiated adenocarcinoma showed a tendency to lower OPRT and higher DPD, as compared to moderately or well-differentiated adenocarcinomas. In case with metastasis to lymph nodes, OPRT showed a tendency to lower activities, but a significant difference was not noticed. TS showed no relation to any of these pathologic factors. In each application of 5-FU, measuring the activities of these three enzymes is important for estimation of the antitumoral effect. With poorly-differentiated adenocarcinoma, it is estimated that many cases would show high DPD and if the enzyme activities can not be measured, so administration of TS-1, which includes DPD inhibitor, may be considered.

Adenocarcinoma↗

PubMed2006

[A case of advanced gastric cancer successfully treated by TS-1 and CDDP after jejunostomy].

A 65-year-old female with unresectable advanced gastric cancer accompanied by multiple lung metastases underwent jejunostomy and was treated with TS-1 and CDDP. One course consisted of TS-1 (80 mg/day) via an intestinal fistula tube from days 1 to 14 followed by 14 days rest and CDDP (80 mg/day) was administered by 24-hour continuous intravenous infusion on day 8. After 3 courses, the primary tumor and lymph node metastases decreased in size (PR), and CT scan showed the multiple lung metastases had disappeared. Total gastrectomy (D 2) and splenectomy were performed after chemotherapy. The final diagnosis was Stage IIIA and the pathological response to chemotherapy was Grade 2. The patient has survived for over 14 months after surgery and has presented no signs of recurrence.

Aged↗

PubMed2006

[Prediction of sensitivity to 5-fluorouracil (5-fu) by metabolic and target enzyme activities in colon cancer].

BACKGROUND: 5-Fluorouracil (5-FU) and its derivatives are widely known as some of the most commonly prescribed anticancer drugs, especially for gastrointestinal cancer. Orotate phosphoribosyl transferase (OPRT), dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) are initial key enzymes in the 5-FU metabolic pathway. The activities of these enzymes may have the potential to affect the chemosensitivity of 5-FU. PURPOSE: This study was designed to investigate the effect of OPRT, DPD and TS in sensitivity to 5-FU. METHOD: We measured OPRT, DPD and TS activities in 11 colonic cancer tissues. The Collagen Gel Droplet Embedded Culture Drug Sensitivity Test (CD-DST) was used in an in vitro chemosensitivity assay. In these samples, the correlation between sensitivity to 5-FU and enzyme activities was investigated. RESULTS: There were no correlations among OPRT, TS activities and sensitivity to 5-FU. In contrast, there was a significant inverse correlation (r=-0.738) between DPD activity and 5-FU sensitivity. With regression analysis, the coefficient of determination of the activity of the three enzymes versus the sensitivity to 5-FU was 0.61. CONCLUSION: Though measuring OPRT, DPD, TS activities is valuable for prediction of sensitivity to 5-FU, DPD is considered to be the most important predictive factor of 5-FU sensitivity. To improve its accuracy, the finding of a fourth factor such as P-glycoprotein and multidrug resistance-associated proteins (MRP), to be added to OPRT, DPD and TS, is desired.

Adenocarcinoma↗

PubMed2005

Michael addition reactions between chiral equivalents of a nucleophilic glycine and (S)- or (R)-3-[(E)-enoyl]-4-phenyl-1,3-oxazolidin-2-ones as a general method for efficient preparation of beta-substituted pyroglutamic acids. Case of topographically controlled stereoselectivity.

This paper describes a systematic study of addition reactions between the chiral Ni(II) complex of the Schiff base of glycine with (S)-o-[N-(N-benzylprolyl)amino]benzophenone and (S)- or (R)-3-[(E)-enoyl]-4-phenyl-1,3-oxazolidin-2-ones as a general and synthetically efficient approach to beta-substituted pyroglutamic acids and relevant compounds. These reactions were shown to occur at room temperature in the presence of nonchelating organic bases and, most notably, with very high (>98% diastereomeric excess (de)) stereoselectivity at both newly formed stereogenic centers. The stereochemical outcome of the reactions was found to be overwhelmingly controlled by the stereochemical preferences of the Michael acceptors, and the chirality of the glycine complex influenced only the reaction rate. Thus, in the reactions of both the (S)-configured Ni(II) complex and the Michael acceptors, the reaction rates were exceptionally high, allowing preparation of the corresponding products with virtually quantitative (>98%) chemical and stereochemical yields. In contrast, reactions of the (S)-configured Ni(II) complex and (R)-configured Michael acceptors proceeded at noticeably lower rates, but the addition products were obtained in high diastereo- and enantiomeric purity. To rationalize the remarkably high and robust stereoselectivity observed in these reactions, we consider an enzyme-substrate-like mode of interaction involving a topographical match or mismatch of two geometric figures. Excellent chemical and stereochemical yields, combined with the simplicity and operational convenience of the experimental procedures, render the present method of immediate use for preparing various beta-substituted pyroglutamic acids and related compounds.

Catalysis↗

PubMed2005

Combinatorial synthesis of an oligosaccharide library by using beta-bromoglycoside-mediated iterative glycosylation of selenoglycosides: rapid expansion of molecular diversity with simple building blocks.

A new method for constructing an oligosaccharide library composed of structurally defined oligosaccharides is presented based on an iterative glycosylation of selenoglycosides. Treatment of 2-acyl-protected selenoglycosides with bromine selectively generates beta-bromoglycosides, which serve as glycosyl cation equivalents in the oligosaccharide synthesis. Thus, the coupling of the bromoglycosides with another selenoglycoside affords the corresponding glycosylated selenoglycosides, which can be directly used to next glycosylation. The iteration of this sequence allows the synthesis of a variety of oligosaccharides including an elicitor active heptasaccharide. A characteristic feature of the iterative glycosylation is that glycosyl donors and acceptors with the same anomeric reactivity can be selectively coupled by activation of the glycosyl donor prior to coupling with the glycosyl acceptor. Therefore, same selenoglycosides can be used for both the glycosyl donors and the acceptors. This feature has been exemplified by a construction of an oligosaccharide library directed to elicitor-active oligosaccharides. The library composed of stereochemically defined oligoglucosides with considerable structural diversity can be constructed starting from simple selenoglycosides.

Carbohydrate Sequence↗

PubMed2005

DNA augments antigenicity of mycobacterial DNA-binding protein 1 and confers protection against Mycobacterium tuberculosis infection in mice.

Mycobacterium consists up to 7% of mycobacterial DNA-binding protein 1 (MDP1) in total cellular proteins. Host immune responses to MDP1 were studied in mice to explore the antigenic properties of this protein. Anti-MDP1 IgG was produced after infection with either bacillus Calmette-Guérin or Mycobacterium tuberculosis in C3H/HeJ mice. However, the level of Ab was remarkably low when purified MDP1 was injected. MDP1 is considered to be associated with DNA in nucleoid, which contains immunostimulatory CpG motif. Therefore, we examined coadministration of MDP1 and DNA derived from M. tuberculosis. Consequently, this procedure significantly enhanced the production of MDP1-specific IgG. Five nanograms of DNA was enough to enhance MDP1-specific IgG production in the administration of 5 microg of MDP1 into mice. Strong immune stimulation by such a small amount of DNA is noteworthy, because >1,000- to 100,000-fold doses of CpG DNAs are used for immune activation. A synthetic peptide-based study showed that B cell epitopes were different between mice administered MDP1 alone and those given a mixture of MDP1 and DNA, suggesting that DNA alters the three-dimensional structure of MDP1. Coadministration of DNA also enhanced MDP1-specific IFN-gamma production and reduced the bacterial burden of a following challenge of M. tuberculosis, showing that MDP1 is a novel vaccine target. Finally, we found that MDP1 remarkably enhanced TLR9-dependent immune stimulation by unmethylated CpG oligo DNA in vitro. To our knowledge, MDP1 is the first protein discovered that remarkably augments the CpG-mediated immune response and is a potential adjuvant for CpG DNA-based immune therapies.

Animals↗

PubMed2005

Novel recombinant BCG and DNA-vaccination against tuberculosis in a cynomolgus monkey model.

We have developed two novel tuberculosis (TB) vaccines: a DNA vaccine combination expressing mycobacterial heat shock protein 65 (Hsp65) and interleukin-12 (IL-12) by using the hemagglutinating virus of Japan (HVJ)-liposome (HSP65+IL-12/HVJ) and a recombinant BCG harboring the 72f fusion gene (72f rBCG). These vaccines provide remarkable protective efficacy in mouse and guinea pig models, as compared to the current by available BCG vaccine. In the present study, we extended our studies to a cynomolgus monkey model, which is currently the best animal model of human tuberculosis, to evaluate the HSP65+IL-12/HVJ and 72f rBCG vaccines. Vaccination with HSP65+IL-12/HVJ as well as 72f rBCG vaccines provided better protective efficacy as assessed by the Erythrocyte Sedimentation Rate, chest X-ray findings and immune responses than BCG. Most importantly, HSP65+IL-12/HVJ resulted in an increased survival for over a year. This is the first report of successful DNA vaccination and recombinant BCG vaccination against M. tuberculosis in the monkey model.

Animals↗

PubMed2005

Physical and functional interactions of the lysophosphatidic acid receptors with PDZ domain-containing Rho guanine nucleotide exchange factors (RhoGEFs).

Lysophosphatidic acid (LPA) is a serum-derived phospholipid that induces a variety of biological responses in various cells via heterotrimeric G protein-coupled receptors (GPCRs) including LPA1, LPA2, and LPA3. LPA-induced cytoskeletal changes are mediated by Rho family small GTPases, such as RhoA, Rac1, and Cdc42. One of these small GTPases, RhoA, may be activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors (RhoGEFs) under LPA stimulation although the detailed mechanisms are poorly understood. Here, we show that the C terminus of LPA1 and LPA2 but not LPA3 interact with the PDZ domains of PDZ domain-containing RhoGEFs, PDZ-RhoGEF, and LARG, which are comprised of PDZ, RGS, Dbl homology (DH), and pleckstrin homology (PH) domains. In LPA1- and LPA2-transfected HEK293 cells, LPA-induced RhoA activation was observed although the C terminus of LPA1 and LPA2 mutants, which failed to interact with the PDZ domains, did not cause LPA-induced RhoA activation. Furthermore, overexpression of the PDZ domains of PDZ domain-containing RhoGEFs served as dominant negative mutants for LPA-induced RhoA activation. Taken together, these results indicate that formation of the LPA receptor/PDZ domain-containing RhoGEF complex plays a pivotal role in LPA-induced RhoA activation.

Animals↗

PubMed2005

Baicalein 5,6,7-trimethyl ether, a flavonoid derivative, stimulates fatty acid beta-oxidation in skin fibroblasts of X-linked adrenoleukodystrophy.

The purpose of the present study is to identify bioactive compounds with potential for X-linked adrenoleukodystrophy (X-ALD) pharmacological therapy. Various plant natural products including flavonoids were tested for their ability to ameliorate the abnormality of very long chain fatty acid (VLCFA) metabolism in cultured skin-fibroblasts from X-ALD patients. Of the compounds tested, baicalein 5,6,7-trimethyl ether (baicalein-tri-Me) was found to significantly stimulate the VLCFA beta-oxidation activity. Furthermore, the incorporation of [1-(14)C]lignoceric acid into cholesteryl esters was markedly reduced towards the normal level and the VLCFA (C24:0 and C26:0) content was decreased. These results make baicalein-tri-Me a candidate for the therapeutic compound for X-ALD.

Adrenoleukodystrophy↗

PubMed2005

Reversed operation of glutamate transporter GLT-1 is crucial to the development of preconditioning-induced ischemic tolerance of neurons in neuron/astrocyte co-cultures.

Sublethal ischemia leads to increased tolerance against subsequent prolonged cerebral ischemia in vivo. In the present study, we investigated the roles of the astrocytic glutamate (Glu) transporter GLT-1 in preconditioning (PC)-induced neuronal ischemic tolerance in cortical neuron/astrocyte co-cultures. Ischemia in vitro was simulated by subjecting cultures to both oxygen and glucose deprivation (OGD). A sublethal OGD (PC) increased the survival rate of neurons significantly when cultures were exposed to a lethal OGD 24 h later. The extracellular concentration of Glu increased significantly during PC, and treatment with an inhibitor of N-methyl-D-actetate (NMDA) receptors significantly reversed the PC-induced ischemic tolerance of neurons, suggesting that the increase in extracellular concentration of Glu during PC was critical to the development of PC-induced neuronal ischemic tolerance via the activation of NMDA receptors. Treatment with a GLT-1 blocker during PC suppressed this increase in Glu significantly, and antagonized the PC-induced neuronal ischemic tolerance. This study suggested that the reversed operation of GLT-1 was crucial to the development of neuronal ischemic tolerance.

Animals↗

PubMed2005

Functional significance of the preconditioning-induced down-regulation of glutamate transporter GLT-1 in neuron/astrocyte co-cultures.

In the brain, prior sublethal ischemia (preconditioning, PC) is known to produce tolerance of neurons to subsequent lethal ischemia. This study aims at elucidating what alterations were induced in neurons and/or astrocytes by PC treatment. The rise in the extracellular concentration of glutamate during ischemia was markedly suppressed by the prior PC treatment. Immunocytochemical and Western blot analyses demonstrated that the expression of the astrocytic glutamate transporter GLT-1 was transiently down-regulated after the PC insult. The PC insult possibly suppressed the neuron-derived factors up-regulating GLT-1. Here we show that PC-induced down-regulation of GLT-1 is crucial for the increased neuronal resistance to subsequent severe ischemic insult.

Animals↗

PubMed2005

Absolute stereostructures of cell-adhesion inhibitors, peribysins A, E, F and G, produced by a sea hare-derived Periconia sp.

Peribysins E-G (1-3) have been isolated from a strain of Periconia byssoides originally separated from the sea hare Aplysia kurodai. Their absolute stereostructures have been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques and some chemical transformations. In addition, the absolute configuration of peribysin A (4), previously undetermined, has been established by conversion to 2 and 3. All these metabolites inhibited the adhesion of human-leukemia HL-60 cells to HUVEC.

Animals↗

PubMed2005

Diversity, localization, and physiological properties of filamentous microbes belonging to Chloroflexi subphylum I in mesophilic and thermophilic methanogenic sludge granules.

We previously reported that the thermophilic filamentous anaerobe Anaerolinea thermophila, which is the first cultured representative of subphylum I of the bacterial phylum Chloroflexi, not only was one of the predominant constituents of thermophilic sludge granules but also was a causative agent of filamentous sludge bulking in a thermophilic (55 degrees C) upflow anaerobic sludge blanket (UASB) reactor in which high-strength organic wastewater was treated (Y. Sekiguchi, H. Takahashi, Y. Kamagata, A. Ohashi, and H. Harada, Appl. Environ. Microbiol. 67:5740-5749, 2001). To further elucidate the ecology and function of Anaerolinea-type filamentous microbes in UASB sludge granules, we surveyed the diversity, distribution, and physiological properties of Chloroflexi subphylum I microbes residing in UASB granules. Five different types of mesophilic and thermophilic UASB sludge were used to analyze the Chloroflexi subphylum I populations. 16S rRNA gene cloning-based analyses using a 16S rRNA gene-targeted Chloroflexi-specific PCR primer set revealed that all clonal sequences were affiliated with the Chloroflexi subphylum I group and that a number of different phylotypes were present in each clone library, suggesting the ubiquity and vast genetic diversity of these populations in UASB sludge granules. Subsequent fluorescence in situ hybridization (FISH) of the three different types of mesophilic sludge granules using a Chloroflexi-specific probe suggested that all probe-reactive cells had a filamentous morphology and were widely distributed within the sludge granules. The FISH observations also indicated that the Chloroflexi subphylum I bacteria were not always the predominant populations within mesophilic sludge granules, in contrast to thermophilic sludge granules. We isolated two mesophilic strains and one thermophilic strain belonging to the Chloroflexi subphylum I group. The physiological properties of these isolates suggested that these populations may contribute to the degradation of carbohydrates and other cellular components, such as amino acids, in the bioreactors.

Chloroflexi↗

PubMed2005

Mycobacterial codon optimization enhances antigen expression and virus-specific immune responses in recombinant Mycobacterium bovis bacille Calmette-Guérin expressing human immunodeficiency virus type 1 Gag.

Although its potential for vaccine development is already known, the introduction of recombinant human immunodeficiency virus (HIV) genes to Mycobacterium bovis bacille Calmette-Guérin (BCG) has thus far elicited only limited responses. In order to improve the expression levels, we optimized the codon usage of the HIV type 1 (HIV-1) p24 antigen gene of gag (p24 gag) and established a codon-optimized recombinant BCG (rBCG)-p24 Gag which expressed a 40-fold-higher level of p24 Gag than did that of nonoptimized rBCG-p24 Gag. Inoculation of mice with the codon-optimized rBCG-p24 Gag elicited effective immunity, as evidenced by virus-specific lymphocyte proliferation, gamma interferon ELISPOT cell induction, and antibody production. In contrast, inoculation of animals with the nonoptimized rBCG-p24 Gag induced only low levels of immune responses. Furthermore, a dose as small as 0.01 mg of the codon-optimized rBCG per animal proved capable of eliciting immune responses, suggesting that even low doses of a codon-optimized rBCG-based vaccine could effectively elicit HIV-1-specific immune responses.

AIDS Vaccines↗